In order to reducing motors energy consumption, the problem about motion function, which has torque feature (AV) m small, is discussed in this paper. Conventional functions and small torque moment function are used to control mass center motion of robot ZQROT-I respectively. In the process of robot running the straight gait , motion performance of the robot is analyzed by ADAMS. Analysis result indicates that function controlling mass motion of robot with small torque feature has significant meaning for saving working energy of robot.