The invention discloses a metallographic polishing clamp. A clamp main body comprises a fixed support module, a rocker arm module and a test piece clamping module. The metallographic polishing clamp is characterized in that the fixed support module is fixed to a polishing machine wheel disc cover and screwed through a screw, a cylindrical guide rod is installed on a fixed support base, a lifting lock on the rocker arm module lifts along the guide rod, and the rocker arm module is composed of a front arm, a rear arm, a lifting block and a connecting block. The front arm and the rear arm can rotate around a shaft on the lifting block and the connecting block. The test piece clamping module is composed of a fixed block, a movable block and a screw rod. The fixed block is connected to the front arm, the movable block is connected to the fixed block and driven by the screw rod to move along the guide rod on the fixed block, and a clamping device is positioned on the movable block and used for clamping a metallographic test piece. The rocker arm module and the test piece clamping module can move randomly in the horizontal plane and can also move up and down, so as to meet the polishing requirements of metallographic test pieces of different dimensions.