Radar level transmitter can perform non-contact continuous measurement of the height of liquids in closed or open containers in industrial production processes. The radar level transmitter has a long detection distance and low beam energy, and can be installed in various metal and non-metal containers or pipelines. It is suitable for occasions where dust, water mist, inert gas and steam exist. The radar level transmitter has no harm to the human body and the environment, and has the advantages of not being affected by the specific gravity of the medium, not being affected by the change of the dielectric constant, and not requiring on-site calibration.