diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/constant/ConstPool.java b/testable-agent/src/main/java/com/alibaba/testable/agent/constant/ConstPool.java
index 63b259e..23c1f7d 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/constant/ConstPool.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/constant/ConstPool.java
@@ -11,6 +11,7 @@ public class ConstPool {
     public static final String TEST_POSTFIX = "Test";
 
     public static final String FIELD_TARGET_METHOD = "targetMethod";
+    public static final String FIELD_TARGET_CLASS = "targetClass";
 
     public static final String MOCK_WITH = "com.alibaba.testable.core.annotation.MockWith";
     public static final String MOCK_METHOD = "com.alibaba.testable.core.annotation.MockMethod";
diff --git a/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java b/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java
index ad5d181..e81fbb0 100644
--- a/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java
+++ b/testable-agent/src/main/java/com/alibaba/testable/agent/transformer/TestableClassTransformer.java
@@ -9,6 +9,7 @@ import com.alibaba.testable.agent.util.AnnotationUtil;
 import com.alibaba.testable.agent.util.ClassUtil;
 import com.alibaba.testable.agent.util.GlobalConfig;
 import com.alibaba.testable.agent.util.StringUtil;
+import com.alibaba.testable.core.model.NullType;
 import com.alibaba.testable.core.util.LogUtil;
 import com.alibaba.testable.core.model.MockDiagnose;
 import org.objectweb.asm.ClassReader;
@@ -131,8 +132,7 @@ public class TestableClassTransformer implements ClassFileTransformer {
     }
 
     private void checkMethodAnnotation(ClassNode cn, List<MethodInfo> methodInfos, MethodNode mn) {
-        ImmutablePair<String, String> methodDescPair = extractFirstParameter(mn.desc);
-        if (methodDescPair == null || mn.visibleAnnotations == null) {
+        if (mn.visibleAnnotations == null) {
             return;
         }
         for (AnnotationNode an : mn.visibleAnnotations) {
@@ -141,6 +141,10 @@ public class TestableClassTransformer implements ClassFileTransformer {
                 addMockConstructor(cn, methodInfos, mn);
             } else if (fullClassName.equals(ConstPool.MOCK_METHOD) ||
                        fullClassName.equals(ConstPool.TESTABLE_MOCK)) {
+                ImmutablePair<String, String> methodDescPair = getMethodDescPair(mn, an);
+                if (methodDescPair == null) {
+                    return;
+                }
                 String targetMethod = AnnotationUtil.getAnnotationParameter(
                     an, ConstPool.FIELD_TARGET_METHOD, mn.name, String.class);
                 if (targetMethod.equals(ConstPool.CONSTRUCTOR)) {
@@ -153,6 +157,16 @@ public class TestableClassTransformer implements ClassFileTransformer {
         }
     }
 
+    private ImmutablePair<String, String> getMethodDescPair(MethodNode mn, AnnotationNode an) {
+        Class<?> targetClass = AnnotationUtil.getAnnotationParameter(
+            an, ConstPool.FIELD_TARGET_CLASS, NullType.class, Class.class);
+        if (targetClass.equals(NullType.class)) {
+            return extractFirstParameter(mn.desc);
+        } else {
+            return ImmutablePair.of(ClassUtil.toByteCodeClassName(targetClass.getName()), mn.desc);
+        }
+    }
+
     private void addMockMethod(List<MethodInfo> methodInfos, MethodNode mn,
                                ImmutablePair<String, String> methodDescPair, String targetMethod) {
         String targetClass = ClassUtil.toSlashSeparateFullClassName(methodDescPair.left);
diff --git a/testable-agent/src/test/java/com/alibaba/testable/agent/transformer/TestableClassTransformerTest.java b/testable-agent/src/test/java/com/alibaba/testable/agent/transformer/TestableClassTransformerTest.java
new file mode 100644
index 0000000..1e189f2
--- /dev/null
+++ b/testable-agent/src/test/java/com/alibaba/testable/agent/transformer/TestableClassTransformerTest.java
@@ -0,0 +1,23 @@
+package com.alibaba.testable.agent.transformer;
+
+import com.alibaba.testable.agent.tool.ImmutablePair;
+import com.alibaba.testable.core.accessor.PrivateAccessor;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TestableClassTransformerTest {
+
+    private TestableClassTransformer testableClassTransformer = new TestableClassTransformer();
+
+    @Test
+    void should_split_parameters() {
+        ImmutablePair<String, String> parameters =
+            PrivateAccessor.invoke(testableClassTransformer, "extractFirstParameter", "()");
+        assertNull(parameters);
+        parameters = PrivateAccessor.invoke(testableClassTransformer, "extractFirstParameter", "(Lcom.alibaba.demo.Class;ILjava.lang.String;Z)");
+        assertNotNull(parameters);
+        assertEquals("Lcom.alibaba.demo.Class;", parameters.left);
+        assertEquals("(ILjava.lang.String;Z)", parameters.right);
+    }
+}
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/annotation/MockMethod.java b/testable-core/src/main/java/com/alibaba/testable/core/annotation/MockMethod.java
index 7733ace..9bc1745 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/annotation/MockMethod.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/annotation/MockMethod.java
@@ -1,6 +1,6 @@
 package com.alibaba.testable.core.annotation;
 
-import javax.lang.model.type.NullType;
+import com.alibaba.testable.core.model.NullType;
 import java.lang.annotation.*;
 
 /**
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/model/NullType.java b/testable-core/src/main/java/com/alibaba/testable/core/model/NullType.java
new file mode 100644
index 0000000..afa5f7a
--- /dev/null
+++ b/testable-core/src/main/java/com/alibaba/testable/core/model/NullType.java
@@ -0,0 +1,7 @@
+package com.alibaba.testable.core.model;
+
+/**
+ * @author flin
+ */
+public interface NullType {
+}