diff --git a/.github/workflows/e2e-test.yaml b/.github/workflows/e2e-test.yaml
index fe645f15..809e37c7 100644
--- a/.github/workflows/e2e-test.yaml
+++ b/.github/workflows/e2e-test.yaml
@@ -95,6 +95,10 @@ jobs:
           echo "********************************************************************************"
           bin/kubecm s kind-2nd-kind --config merge.config
           echo "********************************************************************************"
+          echo "Running kubecm namespace..."
+          echo "********************************************************************************"
+          bin/kubecm ns kube-system
+          echo "********************************************************************************"
           echo "Running kubecm list from env KUBECONFIG..."
           echo "********************************************************************************"
           echo "default config"
diff --git a/cmd/namespace.go b/cmd/namespace.go
index 1b43e3cf..e3eecace 100644
--- a/cmd/namespace.go
+++ b/cmd/namespace.go
@@ -1,8 +1,11 @@
 package cmd
 
 import (
+	"context"
 	"errors"
 	"fmt"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
 	"log"
 	"os"
 	"strings"
@@ -10,7 +13,6 @@ import (
 	"github.com/manifoldco/promptui"
 	"github.com/spf13/cobra"
 	"k8s.io/client-go/tools/clientcmd"
-	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 )
 
 // NamespaceCommand namespace cmd struct
@@ -46,21 +48,31 @@ func (nc *NamespaceCommand) runNamespace(command *cobra.Command, args []string)
 	}
 
 	currentContext := config.CurrentContext
-	contNs := config.Contexts[currentContext].Namespace
-	namespaceList, err := GetNamespaceList(contNs)
+	currentNamespace := config.Contexts[currentContext].Namespace
+	clientset, err := GetClientSet(cfgFile)
 	if err != nil {
 		return err
 	}
 
 	if len(args) == 0 {
+		namespaceList, err := GetNamespaceList(currentNamespace, clientset)
+		if err != nil {
+			return err
+		}
 		// exit option
 		namespaceList = append(namespaceList, Namespaces{Name: "<Exit>", Default: false})
 		num := selectNamespace(namespaceList)
 		config.Contexts[currentContext].Namespace = namespaceList[num].Name
 	} else {
-		err := changeNamespace(args, namespaceList, currentContext, config)
+		exist, err := CheckNamespaceExist(args[0], clientset)
 		if err != nil {
-			return err
+			return errors.New("Can not find namespace: " + args[0])
+		}
+		if exist {
+			config.Contexts[currentContext].Namespace = args[0]
+			fmt.Printf("Namespace: 「%s」 is selected.\n", args[0])
+		} else {
+			return errors.New("Can not find namespace: " + args[0])
 		}
 	}
 	err = WriteConfig(true, cfgFile, config)
@@ -70,17 +82,6 @@ func (nc *NamespaceCommand) runNamespace(command *cobra.Command, args []string)
 	return MacNotifier(fmt.Sprintf("Switch to the [%s] namespace\n", config.Contexts[currentContext].Namespace))
 }
 
-func changeNamespace(args []string, namespaceList []Namespaces, currentContext string, config *clientcmdapi.Config) error {
-	for _, ns := range namespaceList {
-		if ns.Name == args[0] {
-			config.Contexts[currentContext].Namespace = args[0]
-			fmt.Printf("Namespace: 「%s」 is selected.\n", args[0])
-			return nil
-		}
-	}
-	return errors.New("Can not find namespace: " + args[0])
-}
-
 func selectNamespace(namespaces []Namespaces) int {
 	ns, err := selectNamespaceWithRunner(namespaces, nil)
 	if err != nil {
@@ -128,6 +129,53 @@ func selectNamespaceWithRunner(namespaces []Namespaces, runner SelectRunner) (in
 	return i, err
 }
 
+// GetClientSet return clientset
+func GetClientSet(configFile string) (kubernetes.Interface, error) {
+	config, err := clientcmd.BuildConfigFromFlags("", configFile)
+	if err != nil {
+		return nil, fmt.Errorf(err.Error())
+	}
+	return kubernetes.NewForConfig(config)
+}
+
+// GetNamespaceList return namespace list
+func GetNamespaceList(currentNamespace string, clientset kubernetes.Interface) ([]Namespaces, error) {
+	var nss []Namespaces
+	namespaceList, err := clientset.CoreV1().Namespaces().List(context.TODO(), metav1.ListOptions{})
+	if err != nil {
+		return nil, fmt.Errorf(err.Error())
+	}
+	for _, specItem := range namespaceList.Items {
+		switch currentNamespace {
+		case "":
+			if specItem.Name == "default" {
+				nss = append(nss, Namespaces{Name: specItem.Name, Default: true})
+			} else {
+				nss = append(nss, Namespaces{Name: specItem.Name, Default: false})
+			}
+		default:
+			if specItem.Name == currentNamespace {
+				nss = append(nss, Namespaces{Name: specItem.Name, Default: true})
+			} else {
+				nss = append(nss, Namespaces{Name: specItem.Name, Default: false})
+			}
+		}
+	}
+	return nss, nil
+}
+
+// CheckNamespaceExist check namespace exist
+func CheckNamespaceExist(namespace string, clientset kubernetes.Interface) (bool, error) {
+	ns, err := clientset.CoreV1().Namespaces().Get(context.TODO(), namespace, metav1.GetOptions{})
+	if err != nil {
+		return false, fmt.Errorf(err.Error())
+	}
+	if ns.Name == namespace {
+		return true, nil
+	}
+	return false, errors.New("namespace not found")
+}
+
 func namespaceExample() string {
 	return `
 # Switch Namespace interactively
diff --git a/cmd/namespace_test.go b/cmd/namespace_test.go
index aabbbb7b..e2fe8931 100644
--- a/cmd/namespace_test.go
+++ b/cmd/namespace_test.go
@@ -1,77 +1,17 @@
 package cmd
 
 import (
+	"context"
 	"errors"
-	"fmt"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/kubernetes/fake"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
-
-	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 )
 
-var (
-	testNsConfig = clientcmdapi.Config{
-		AuthInfos: map[string]*clientcmdapi.AuthInfo{
-			"black-user": {Token: "black-token"},
-			"red-user":   {Token: "red-token"},
-		},
-		Clusters: map[string]*clientcmdapi.Cluster{
-			"pig-cluster": {Server: "http://pig.org:8080"},
-			"cow-cluster": {Server: "http://cow.org:8080"},
-		},
-		Contexts: map[string]*clientcmdapi.Context{
-			"root-context":    {AuthInfo: "black-user", Cluster: "pig-cluster", Namespace: "saw-ns"},
-			"federal-context": {AuthInfo: "red-user", Cluster: "cow-cluster", Namespace: "hammer-ns"},
-		},
-	}
-)
-
-func Test_changeNamespace(t *testing.T) {
-	type args struct {
-		args           []string
-		namespaceList  []Namespaces
-		currentContext string
-		config         *clientcmdapi.Config
-	}
-	tests := []struct {
-		name    string
-		args    args
-		wantErr bool
-	}{
-		// TODO: Add test cases.
-		{
-			"ns",
-			args{args: []string{"test"},
-				namespaceList: []Namespaces{
-					{"test", false},
-					{"hammer-ns", true}},
-				currentContext: "root-context",
-				config:         &testNsConfig},
-			false,
-		},
-		{
-			"ns-not-exit",
-			args{args: []string{"a"},
-				namespaceList: []Namespaces{
-					{"test", false},
-					{"hammer-ns", true}},
-				currentContext: "root-context",
-				config:         &testNsConfig},
-			true,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if err := changeNamespace(tt.args.args, tt.args.namespaceList, tt.args.currentContext, tt.args.config); (err != nil) != tt.wantErr {
-				t.Errorf("changeNamespace() error = %v, wantErr %v", err, tt.wantErr)
-			} else {
-				fmt.Printf("Catch ERROR: %v\n", err)
-			}
-		})
-	}
-}
-
 type testSelectNamespacePrompt struct {
 	index int
 	err   error
@@ -136,3 +76,150 @@ func TestSelectNamespace(t *testing.T) {
 		})
 	}
 }
+
+func TestCheckNamespaceExist(t *testing.T) {
+	// Define test cases
+	testCases := []struct {
+		name        string
+		namespace   string
+		namespaces  []string
+		expectExist bool
+		expectError bool
+	}{
+		{
+			name:        "Namespace exists",
+			namespace:   "test",
+			namespaces:  []string{"default", "test"},
+			expectExist: true,
+			expectError: false,
+		},
+		{
+			name:        "Namespace does not exist",
+			namespace:   "nonexistent",
+			namespaces:  []string{"default", "test"},
+			expectExist: false,
+			expectError: true,
+		},
+		{
+			name:        "Error case",
+			namespace:   "",
+			namespaces:  nil, // Assuming this simulates an error condition
+			expectExist: false,
+			expectError: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			clientset := mockKubernetesClientSet(tc.namespaces)
+			exist, err := CheckNamespaceExist(tc.namespace, clientset)
+			if tc.expectError {
+				if err == nil {
+					t.Errorf("Expected an error, but got none")
+				}
+			} else {
+				if err != nil {
+					t.Errorf("Unexpected error: %v", err)
+				}
+				if exist != tc.expectExist {
+					t.Errorf("Expected existence to be %v, got %v", tc.expectExist, exist)
+				}
+			}
+		})
+	}
+}
+
+func TestGetNamespaceList(t *testing.T) {
+	testCases := []struct {
+		name             string
+		currentNamespace string
+		namespaces       []string
+		expected         []Namespaces
+		expectError      bool
+	}{
+		{
+			name:             "Success with default namespace",
+			currentNamespace: "default",
+			namespaces:       []string{"default", "test"},
+			expected: []Namespaces{
+				{Name: "default", Default: true},
+				{Name: "test", Default: false},
+			},
+			expectError: false,
+		},
+		{
+			name:             "Success with specified namespace",
+			currentNamespace: "test",
+			namespaces:       []string{"default", "test"},
+			expected: []Namespaces{
+				{Name: "default", Default: false},
+				{Name: "test", Default: true},
+			},
+			expectError: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			clientset := mockKubernetesClientSet(tc.namespaces)
+			nss, err := GetNamespaceList(tc.currentNamespace, clientset)
+			if tc.expectError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tc.expected, nss)
+			}
+		})
+	}
+}
+
+// mockKubernetesClientSet creates a mock clientset that contains the provided namespaces.
+func mockKubernetesClientSet(namespaces []string) kubernetes.Interface {
+	clientset := fake.NewSimpleClientset()
+
+	for _, ns := range namespaces {
+		namespace := &corev1.Namespace{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: ns,
+			},
+		}
+		_, err := clientset.CoreV1().Namespaces().Create(context.TODO(), namespace, metav1.CreateOptions{})
+		if err != nil {
+			return nil
+		}
+	}
+
+	return clientset
+}
+
+func TestGetClientSet(t *testing.T) {
+	// Create a fake clientset
+	clientset := fake.NewSimpleClientset()
+
+	// Create a namespace object
+	namespace := &corev1.Namespace{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "default",
+		},
+	}
+
+	// Add the namespace to the fake clientset
+	_, err := clientset.CoreV1().Namespaces().Create(context.Background(), namespace, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatalf("Could not create namespace: %v", err)
+	}
+
+	// Use the clientset to get the list of namespaces
+	namespaces, err := clientset.CoreV1().Namespaces().List(context.Background(), metav1.ListOptions{})
+	if err != nil {
+		t.Fatalf("Could not list namespaces: %v", err)
+	}
+
+	// Check that the "default" namespace exists
+	for _, ns := range namespaces.Items {
+		if ns.Name == "default" {
+			return
+		}
+	}
+	t.Fatal("Did not find 'default' namespace")
+}
diff --git a/cmd/utils.go b/cmd/utils.go
index 546a729f..18000548 100644
--- a/cmd/utils.go
+++ b/cmd/utils.go
@@ -354,41 +354,6 @@ func ExitOption(kubeItems []Needle) ([]Needle, error) {
 	return kubeItems, nil
 }
 
-// GetNamespaceList return namespace list
-func GetNamespaceList(cont string) ([]Namespaces, error) {
-	var nss []Namespaces
-	config, err := clientcmd.BuildConfigFromFlags("", cfgFile)
-	if err != nil {
-		return nil, fmt.Errorf(err.Error())
-	}
-	clientset, err := kubernetes.NewForConfig(config)
-	if err != nil {
-		return nil, fmt.Errorf(err.Error())
-	}
-	ctx := context.TODO()
-	namespaceList, err := clientset.CoreV1().Namespaces().List(ctx, metav1.ListOptions{})
-	if err != nil {
-		return nil, fmt.Errorf(err.Error())
-	}
-	for _, specItem := range namespaceList.Items {
-		switch cont {
-		case "":
-			if specItem.Name == "default" {
-				nss = append(nss, Namespaces{Name: specItem.Name, Default: true})
-			} else {
-				nss = append(nss, Namespaces{Name: specItem.Name, Default: false})
-			}
-		default:
-			if specItem.Name == cont {
-				nss = append(nss, Namespaces{Name: specItem.Name, Default: true})
-			} else {
-				nss = append(nss, Namespaces{Name: specItem.Name, Default: false})
-			}
-		}
-	}
-	return nss, nil
-}
-
 func printService(out io.Writer, name, link string) {
 	ct.ChangeColor(ct.Green, false, ct.None, false)
 	fmt.Fprint(out, name)