The sensor of the ultrasonic flowmeter consists of two parts: One part is the transmitting part, which transforms electric energy into acoustic energy at a certain frequency and  send it out, the other part is the receiving part, which transforms the acoustic energy into electric energy and receive it; The speed of sound is proportional to the flow velocity of the fluid, the flow velocity of the fluid can be calculated according through the propagation velocity of sound velocity, and the flow of fluid can be determined.