The working path of the palletizing robot was expounded, and the forward and inverse kinematics solutions were carried out according to the D-H parameters and the coordinate transformation diagram of each joint of the robot. Trajectory planning in joint space and Cartesian space for robot palletizing task was conducted by MATLAB. Considering the requirements of pulsation continuity and reducing computation, POS optimization algorithm was applied to solve the optimal time of polynomial trajectory of 3-5-3 times for a stacking cycle of a stacking robot under the condition of maximum speed constraint, which solved the problems of high order of polynomial trajectory planning, large computation and lack of convex hull.