diff --git a/demo/java-demo/src/main/java/com/alibaba/testable/demo/DemoPrivateAccess.java b/demo/java-demo/src/main/java/com/alibaba/testable/demo/DemoPrivateAccess.java
index bb465de..ebd0fa1 100644
--- a/demo/java-demo/src/main/java/com/alibaba/testable/demo/DemoPrivateAccess.java
+++ b/demo/java-demo/src/main/java/com/alibaba/testable/demo/DemoPrivateAccess.java
@@ -18,22 +18,6 @@ public class DemoPrivateAccess {
      */
     public final Double pi = 3.14;
 
-    /**
-     * method accessing private static field
-     */
-    public static String privateStaticFieldAccessFunc() {
-        staticCount += 3;
-        return String.valueOf(staticCount);
-    }
-
-    /**
-     * method accessing private member field
-     */
-    public String privateFieldAccessFunc() {
-        count += 2;
-        return String.valueOf(count);
-    }
-
     /**
      * private static method
      */
diff --git a/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoPrivateAccessTest.java b/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoPrivateAccessTest.java
index 366c3bb..cafb0f3 100644
--- a/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoPrivateAccessTest.java
+++ b/demo/java-demo/src/test/java/com/alibaba/testable/demo/DemoPrivateAccessTest.java
@@ -20,12 +20,10 @@ class DemoPrivateAccessTest {
     @Test
     void should_able_to_access_private_field() throws Exception {
         demoPrivateAccess.count = 2;
-        assertEquals("4", demoPrivateAccess.privateFieldAccessFunc());
-        assertEquals(new Integer(4), demoPrivateAccess.count);
+        assertEquals(new Integer(2), demoPrivateAccess.count);
 
         PrivateAccessor.set(demoPrivateAccess, "count", 3);
-        assertEquals("5", demoPrivateAccess.privateFieldAccessFunc());
-        assertEquals(new Integer(5), PrivateAccessor.get(demoPrivateAccess, "count"));
+        assertEquals(new Integer(3), PrivateAccessor.get(demoPrivateAccess, "count"));
     }
 
     @Test
@@ -37,12 +35,10 @@ class DemoPrivateAccessTest {
     @Test
     void should_able_to_access_private_static_field() throws Exception {
         //DemoPrivateAccess.staticCount = 2;
-        //assertEquals("5", DemoPrivateAccess.privateStaticFieldAccessFunc());
-        //assertEquals(new Integer(5), DemoPrivateAccess.staticCount);
+        //assertEquals(new Integer(2), DemoPrivateAccess.staticCount);
 
         PrivateAccessor.setStatic(DemoPrivateAccess.class, "staticCount", 3);
-        assertEquals("6", DemoPrivateAccess.privateStaticFieldAccessFunc());
-        assertEquals(new Integer(6), PrivateAccessor.getStatic(DemoPrivateAccess.class, "staticCount"));
+        assertEquals(new Integer(3), PrivateAccessor.getStatic(DemoPrivateAccess.class, "staticCount"));
     }
 
     @Test
diff --git a/demo/kotlin-demo/src/main/kotlin/com/alibaba/testable/demo/DemoPrivateAccess.kt b/demo/kotlin-demo/src/main/kotlin/com/alibaba/testable/demo/DemoPrivateAccess.kt
index fb1e574..adfe0d5 100644
--- a/demo/kotlin-demo/src/main/kotlin/com/alibaba/testable/demo/DemoPrivateAccess.kt
+++ b/demo/kotlin-demo/src/main/kotlin/com/alibaba/testable/demo/DemoPrivateAccess.kt
@@ -2,23 +2,43 @@ package com.alibaba.testable.demo
 
 class DemoPrivateAccess {
 
+    /**
+     * a private member field
+     */
     private var count = 0
 
-    final val pi = 3.14
+    /**
+     * a constant field
+     */
+    val pi = 3.14
 
     /**
-     * private method
+     * private member method
      */
     private fun privateFunc(s: String, i: Int): String {
         return "$s - $i"
     }
 
-    /**
-     * method with private field access
-     */
-    fun privateFieldAccessFunc(): String {
-        count += 2
-        return count.toString()
+    companion object {
+
+        /**
+         * a private static field
+         */
+        private var staticCount = 0
+
+        /**
+         * private static method
+         */
+        private fun privateStaticFunc(s: String, i: Int): String {
+            return "$s + $i"
+        }
+
+        /**
+         * private jvm static method
+         */
+        @JvmStatic private fun privateJvmStaticFunc(s: String, i: Int): String {
+            return "$s * $i"
+        }
     }
 
 }
diff --git a/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoPrivateAccessTest.kt b/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoPrivateAccessTest.kt
index 317ffb7..177afcc 100644
--- a/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoPrivateAccessTest.kt
+++ b/demo/kotlin-demo/src/test/kotlin/com/alibaba/testable/demo/DemoPrivateAccessTest.kt
@@ -17,8 +17,19 @@ internal class DemoPrivateAccessTest {
     @Test
     fun should_able_to_access_private_field() {
         PrivateAccessor.set(demoPrivateAccess, "count", 3)
-        assertEquals("5", demoPrivateAccess.privateFieldAccessFunc())
-        assertEquals(5, PrivateAccessor.get(demoPrivateAccess, "count"))
+        assertEquals(3, PrivateAccessor.get(demoPrivateAccess, "count"))
+    }
+
+    @Test
+    fun should_able_to_access_private_static_method() {
+        assertEquals("hello + 1", PrivateAccessor.invokeStatic(DemoPrivateAccess::class.java, "privateStaticFunc", "hello", 1))
+        assertEquals("hello * 1", PrivateAccessor.invokeStatic(DemoPrivateAccess::class.java, "privateJvmStaticFunc", "hello", 1))
+    }
+
+    @Test
+    fun should_able_to_access_private_static_field() {
+        PrivateAccessor.setStatic(DemoPrivateAccess::class.java, "staticCount", 3)
+        assertEquals(3, PrivateAccessor.getStatic(DemoPrivateAccess::class.java, "staticCount"))
     }
 
     @Test
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/accessor/PrivateAccessor.java b/testable-core/src/main/java/com/alibaba/testable/core/accessor/PrivateAccessor.java
index e02b3b7..d95e60e 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/accessor/PrivateAccessor.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/accessor/PrivateAccessor.java
@@ -10,6 +10,8 @@ import java.lang.reflect.Method;
  */
 public class PrivateAccessor {
 
+    private static final String KOTLIN_COMPANION_FIELD = "Companion";
+
     public static <T> T get(Object ref, String field) {
         try {
             Field declaredField = ref.getClass().getDeclaredField(field);
@@ -75,6 +77,15 @@ public class PrivateAccessor {
                 declaredMethod.setAccessible(true);
                 return (T)declaredMethod.invoke(null, args);
             }
+            // fit kotlin companion object, will throw 'NoSuchFieldException' otherwise
+            Field companionClassField = clazz.getDeclaredField(KOTLIN_COMPANION_FIELD);
+            declaredMethod = TypeUtil.getMethodByNameAndParameterTypes(
+                companionClassField.getType().getDeclaredMethods(), method, cls);
+            Object companionInstance = getStatic(clazz, KOTLIN_COMPANION_FIELD);
+            if (declaredMethod != null && companionInstance != null) {
+                declaredMethod.setAccessible(true);
+                return (T)declaredMethod.invoke(companionInstance, args);
+            }
         } catch (Exception e) {
             System.err.println("Failed to invoke private static method \"" + method + "\": " + e.toString());
             return null;
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java b/testable-core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java
index cf24302..bd4da15 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/util/TestableUtil.java
@@ -67,7 +67,6 @@ public class TestableUtil {
                 }
             }
         }
-        System.err.println("testCaseName: " + testCaseName);
         return testCaseName;
     }