diff --git a/src/main/java/com/alibaba/druid/mock/MockResultSet.java b/src/main/java/com/alibaba/druid/mock/MockResultSet.java
index f73d0d3161..4ef5b0aa9b 100644
--- a/src/main/java/com/alibaba/druid/mock/MockResultSet.java
+++ b/src/main/java/com/alibaba/druid/mock/MockResultSet.java
@@ -736,20 +736,17 @@ public class MockResultSet implements ResultSet {
 
     @Override
     public Ref getRef(int columnIndex) throws SQLException {
-
-        return null;
+        return (Ref) getObject(columnIndex);
     }
 
     @Override
     public Blob getBlob(int columnIndex) throws SQLException {
-
-        return null;
+        return (Blob) getObject(columnIndex);
     }
 
     @Override
     public Clob getClob(int columnIndex) throws SQLException {
-
-        return null;
+        return (Clob) getObject(columnIndex);
     }
 
     @Override
diff --git a/src/test/java/com/alibaba/druid/bvt/proxy/filter/ClobTest.java b/src/test/java/com/alibaba/druid/bvt/proxy/filter/ClobTest.java
new file mode 100644
index 0000000000..cbc60f4231
--- /dev/null
+++ b/src/test/java/com/alibaba/druid/bvt/proxy/filter/ClobTest.java
@@ -0,0 +1,64 @@
+package com.alibaba.druid.bvt.proxy.filter;
+
+import java.sql.Blob;
+import java.sql.Clob;
+import java.sql.Connection;
+import java.sql.NClob;
+import java.sql.ResultSet;
+import java.sql.RowId;
+import java.sql.SQLXML;
+import java.sql.Statement;
+
+import junit.framework.TestCase;
+
+import org.junit.Assert;
+
+import com.alibaba.druid.pool.DruidDataSource;
+
+public class ClobTest extends TestCase {
+
+    public void test_clob() throws Exception {
+        DruidDataSource dataSource = new DruidDataSource();
+        dataSource.setFilters("stat");
+        dataSource.setUrl("jdbc:mock:");
+
+        Connection conn = dataSource.getConnection();
+        Statement stmt = conn.createStatement();
+        ResultSet rs = stmt.executeQuery("SELECT NULL");
+
+        Assert.assertTrue(rs.next());
+        
+        {
+            Clob x = rs.getClob(1);
+            Assert.assertNull(x);
+        }
+
+        {
+            NClob x = rs.getNClob(1);
+            Assert.assertNull(x);
+        }
+
+        {
+            Blob x = rs.getBlob(1);
+            Assert.assertNull(x);
+        }
+
+        {
+            SQLXML x = rs.getSQLXML(1);
+            Assert.assertNull(x);
+        }
+
+        {
+            String x = rs.getString(1);
+            Assert.assertNull(x);
+        }
+
+        Assert.assertNull(rs.getRowId(1));
+        Assert.assertNull(rs.getBigDecimal(1));
+        Assert.assertNull(rs.getObject(1));
+
+        rs.close();
+        stmt.close();
+        conn.close();
+    }
+}