The urea pump test bench is the core component of SCR system, which is called "urea metering pump". Its main function is to pump urea solution out of the urea tank and deliver the urea solution to the nozzle through the transmission pipeline. Its internal composition is mainly composed of diaphragm pump, electromagnetic directional valve, pressure sensor, urea filter element, electric heating system, lead frame and other components. The outside is composed of three urea solution pipelines, namely, liquid injection pipe, liquid return pipe and liquid inlet pipe, which are mainly divided into two types.