Ultrasonic thickness gauge is a high-precision thickness gauge that utilizes the principle of ultrasonic measurement and adopts a high-speed processor and high-integrated chip design to achieve portable, non-destructive, fast and accurate measurement of thickness and sound velocity of various materials. The ultrasonic thickness gauge is suitable for measuring the thickness of various materials, such as steel, various metals, glass, ABS, plastic, PVC, and ductile iron, that can use ultrasonic waves to propagate inside it at a constant speed and can be reflected from the back.