In order to make the lower limb prosthesis to interact with the human body on the slope terrain, the trajectory planning method of the slope terrain for lower limb is developed based on the analysis of slope movement pattern for wearers of lower limb prosthesis, and the simulated motion trajectory of the prosthetic knee joint is obtained. The idea of linearization of tight format is used to solve the nonlinear problem of the lower limb joint, a model free dynamic matrix control method is applied to track the simulated motion trajectory. The methods of feedback correction and rolling optimization are used to realize the predictive output of lower limb prosthetic knee joint angle, and the stability of the control system is analyzed. The feasibility of this approach is verified via simulation and motion control experiments. The results show that the sloping motion trajectory of the prosthetic knee joint closely follows the referenced trajectory, and the prosthetic knee joint and the healthy limb could coordinate smoothly.