In order to improve the efficiency of Hydraulic Machinery Continuously Variable Transmission (HMCVT), studying the efficiency of its pump-controlled motor system is of great significance to promote the practical application of HMCVT in agricultural machinery. By analyzing the HMCVT transmission principle and the driving parameters of medium and large vehicles, determine the HMCVT transmission scheme that meets the actual requirements. The simulation model of the whole HMCVT system was established by SimulationX software, and the relationship curves between different engine speeds and HMCVT output speeds were given. And determine the effect of the pump-controlled motor system on the response parameters of HMCVT under different volumetric efficiency.