Abstract: This paper utilizes the gradient projection method proposed by Dubey to plan the seven DOF 155HP-1 robot manipulator trajectories.The 155HP-1 manipulator contains a prismatic degree,and performs a complex pick-place task in a closed and multi-obstacle space.The manipulator singurality is analyzed,and obstacle avoidance is simplified.During trajectories planning,a simplified Jacobian matrix is adopted,and joint-limit avoidance is taken as optimal performance index,At last,a 2-dimension simulatiOn is given to verify the planned result.