Motor pump is a new type of hydraulic power, which has a large power density, the advantages of compact structure and low noise compared with traditional hydraulic pump. However, due to its high motor pump integration, little research of motor pump movement has been done at home and abroad. Based on the kinematical equation of motor pump valve and piston, simulation model is established by using AMESim. Through simulation response curves of port valve and piston of motor pump are obtained,it shows port valve work normally and the data lay a foundation for the further optimization design of the motor pump.