In order to shorten the product development cycle,a hardware in the loop simulation method of parallel hydraulic hybrid system was proposed.The input/output torque and speed of the hydraulic hybrid system were collected in real time by using torque and speed sensor,and the accumulator pressure was collected in real time by using pressure sensor.According to the backward simulation vehicle and control strategy model running in real time in the upper computer,the engine torque and speed were calculated,and the fuel consumption of the whole vehicle under cycle conditions was obtained in real time.In this method,few physical parts were used,and the control system was simple.This method was compared with the computer simulation method.The results show that by using this method,the speed following error of the electric dynamometer is small,the variation trend of pump motor torque,engine torque,accumulator pressure and vehicle fuel consumption is consistent,and the errors of accumulator pressure and vehicle fuel consumption are within 10%; the accuracy of the hydraulic hybrid system model and the effectiveness of the vehicle control strategy are quickly verified.