diff --git a/plugins/processor/base64/decoding/processor_base64_decoding_test.go b/plugins/processor/base64/decoding/processor_base64_decoding_test.go
new file mode 100644
index 0000000000..66de611e33
--- /dev/null
+++ b/plugins/processor/base64/decoding/processor_base64_decoding_test.go
@@ -0,0 +1,104 @@
+// Copyright 2021 iLogtail 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 decoding
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/alibaba/ilogtail"
+	"github.com/alibaba/ilogtail/pkg/logger"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/alibaba/ilogtail/pkg/protocol"
+	"github.com/alibaba/ilogtail/plugins/test/mock"
+)
+
+func init() {
+	logger.InitTestLogger(logger.OptionOpenMemoryReceiver)
+}
+
+func newProcessor() (*ProcessorBase64Decoding, error) {
+	ctx := mock.NewEmptyContext("p", "l", "c")
+	processor := &ProcessorBase64Decoding{
+		SourceKey: "src",
+		NewKey:    "dest",
+	}
+	err := processor.Init(ctx)
+	return processor, err
+}
+
+func TestSourceKey(t *testing.T) {
+	processor, err := newProcessor()
+	require.NoError(t, err)
+	log := &protocol.Log{Time: 0}
+	value := "MTIz"
+	log.Contents = append(log.Contents, &protocol.Log_Content{Key: "src", Value: value})
+	processor.ProcessLogs([]*protocol.Log{log})
+	assert.Equal(t, "MTIz", log.Contents[0].Value)
+	assert.Equal(t, "123", log.Contents[1].Value)
+}
+
+func TestDecodeError(t *testing.T) {
+	logger.ClearMemoryLog()
+	ctx := mock.NewEmptyContext("p", "l", "c")
+	processor := &ProcessorBase64Decoding{
+		SourceKey:   "src",
+		NewKey:      "dest",
+		DecodeError: true,
+	}
+	err := processor.Init(ctx)
+	require.NoError(t, err)
+	log := &protocol.Log{Time: 0}
+	log.Contents = append(log.Contents, &protocol.Log_Content{Key: "src", Value: "test_value"})
+	processor.ProcessLogs([]*protocol.Log{log})
+	memoryLog, ok := logger.ReadMemoryLog(1)
+	assert.True(t, ok)
+	assert.Equal(t, 1, logger.GetMemoryLogCount())
+	assert.True(t, strings.Contains(memoryLog, "AlarmType:BASE64_D_ALARM\tdecode base64 error"))
+}
+
+func TestNoKeyError(t *testing.T) {
+	logger.ClearMemoryLog()
+	ctx := mock.NewEmptyContext("p", "l", "c")
+	processor := &ProcessorBase64Decoding{
+		SourceKey:  "src",
+		NewKey:     "dest",
+		NoKeyError: true,
+	}
+	err := processor.Init(ctx)
+	require.NoError(t, err)
+	log := &protocol.Log{Time: 0}
+	log.Contents = append(log.Contents, &protocol.Log_Content{Key: "test_key", Value: "test_value"})
+	processor.ProcessLogs([]*protocol.Log{log})
+	memoryLog, ok := logger.ReadMemoryLog(1)
+	assert.True(t, ok)
+	assert.Equal(t, 1, logger.GetMemoryLogCount())
+	assert.True(t, strings.Contains(memoryLog, "AlarmType:BASE64_D_FIND_ALARM\tcannot find key:src"))
+}
+
+func TestDescription(t *testing.T) {
+	processor, err := newProcessor()
+	require.NoError(t, err)
+	assert.Equal(t, processor.Description(), "base64 decoding processor for logtail")
+}
+
+func TestInit(t *testing.T) {
+	p := ilogtail.Processors["processor_base64_decoding"]()
+	assert.Equal(t, reflect.TypeOf(p).String(), "*decoding.ProcessorBase64Decoding")
+}