diff --git a/references/cli/adopt.go b/references/cli/adopt.go
index a54ca22fa..72688044f 100644
--- a/references/cli/adopt.go
+++ b/references/cli/adopt.go
@@ -52,6 +52,7 @@ import (
 	velacmd "github.com/oam-dev/kubevela/pkg/cmd"
 	cmdutil "github.com/oam-dev/kubevela/pkg/cmd/util"
 	"github.com/oam-dev/kubevela/pkg/utils/apply"
+	"github.com/oam-dev/kubevela/pkg/utils/env"
 	"github.com/oam-dev/kubevela/pkg/utils/util"
 )
 
@@ -133,6 +134,9 @@ func (opt *AdoptOptions) parseResourceRef(f velacmd.Factory, cmd *cobra.Command,
 		or.Name = parts[1]
 		if mapping.Scope.Name() == meta.RESTScopeNameNamespace {
 			or.Namespace = velacmd.GetNamespace(f, cmd)
+			if or.Namespace == "" {
+				or.Namespace = env.DefaultEnvNamespace
+			}
 		}
 	case 3:
 		or.Namespace = parts[1]
@@ -160,6 +164,9 @@ func (opt *AdoptOptions) Complete(f velacmd.Factory, cmd *cobra.Command, args []
 		}) {
 			opt.AppName = opt.NativeResourceRefs[0].Name
 		}
+		if opt.AppNamespace == "" {
+			opt.AppNamespace = opt.NativeResourceRefs[0].Namespace
+		}
 	case adoptTypeHelm:
 		if len(args) > 0 {
 			opt.HelmReleaseName = args[0]
diff --git a/references/cli/adopt_test.go b/references/cli/adopt_test.go
new file mode 100644
index 000000000..d9e8e89f2
--- /dev/null
+++ b/references/cli/adopt_test.go
@@ -0,0 +1,58 @@
+/*
+Copyright 2021 The KubeVela Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cli
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/controller-runtime/pkg/client/config"
+
+	velacmd "github.com/oam-dev/kubevela/pkg/cmd"
+	"github.com/oam-dev/kubevela/pkg/utils/util"
+)
+
+func TestDefaultNamespace(t *testing.T) {
+	testcase := []struct {
+		namespace string
+		args      []string
+	}{
+		{
+			namespace: "kube-system",
+			args:      []string{"deployment/kube-system/metrics-server"},
+		},
+		{
+			namespace: "default",
+			args:      []string{"deployment/metrics-server"},
+		},
+	}
+
+	for _, c := range testcase {
+		opt := &AdoptOptions{
+			Type: adoptTypeNative,
+			Mode: adoptModeReadOnly,
+		}
+		f := velacmd.NewDeferredFactory(config.GetConfig)
+		ioStream := util.IOStreams{}
+		cmd := NewAdoptCommand(f, ioStream)
+		err := opt.Complete(f, cmd, c.args)
+		if err != nil {
+			t.Fatalf("failed to parse resourceRef: %v", err)
+		}
+		assert.Equal(t, opt.AppNamespace, c.namespace)
+	}
+}