This millimeter wave radar transmits and receives millimeter wave signals, and processes and analyzes the signals to obtain height and distance information. The working frequency of the millimeter wave radar is 80GHz. When this millimeter wave signal encounters the water surface, it will be reflected. After the reflected signal is received by the millimeter wave radar, through signal processing and analysis, the height information of the water surface can be obtained. By continuously transmitting and receiving millimeter wave signals, the millimeter wave radar can obtain water surface height information in real time and convert it into water level data. At the same time, the millimeter wave radar also has the advantages of high precision, strong anti-interference ability, and all-weather operation. It can be widely used in fields such as water level monitoring and flood warning. This product is small in size and simple to assemble on site. It adopts an industrial-grade casing with a protection level of IP67 and is suitable for use in industrial scenarios.