At present, there are all kinds of methods for hardness measurement commonly used like Brinell, Rockwell, Vickers, Leeb, etc. Rockwell and Brinell with heavy loading force and large indentation lead to serious destruction on sample surfaces. Ultrasonic Hardness Testers apply ultrasonic contact impedance method to do comparative hardness measurements, with the advantage of high accuracy, portability, efficiency, and easy operation.