The product is measured using the Doppler effect principle of underwater ultrasonic acoustics. The sensor emits continuous fixed frequency ultrasonic signals to the water body in front of it, and calculates the moving speed by receiving the frequency deviation of the reflected sound waves from acoustic scatterers (such as particles, bubbles, impurities, etc.) that move with the water body. The moving speed is then corrected to the water flow velocity through vector correction. There is a pressure element at the bottom of the sensor that can sense changes in water pressure and obtain water level signals. Based on the preset size parameters of the river channel (waterway, pipeline), the water passage area can be calculated and flow data can be obtained.