Abstract: In order to implement stable movement on slopes, the shins of quadruped robot were designed to use the hydraulic cylinder in this paper. A mass center adjustment method of quadruped robot was proposed based on trot gait, implemented by decreasing the length of the front shins and keeping the length of the rear shins no change. Firstly,the robot stability was judged according to the superposition degree between the projection point of the mass center and the cross point of the supporting diagonals, and the definite relationship of attitude adjustment was got. Then, a planning method of foot trajectory of no-impact complex cycloid was improved to reduce the contact impact of robot moving on slopes. Finally, the robot moving on slopes in trot gait was simulated by using Adams and Matlab. The simulation results show that, the robot can move steadily on 20° slope with trot gait by using the proposed method of mass center adjustment and the planning method of foot trajectory.