The work aims to realize the smooth and stable speed and acceleration change curves of multi-axis palletizing robots, and simplify the trajectory planning algorithm. Firstly, the structure of palletizing robot was introduced. Based on the structure of palletizing robot, the motion of palletizing robot was analyzed, and a palletizing robot trajectory planning method with a quintic polynomial interpolation in joint space was proposed. The quintic function was used for the interpolation fitting of each joint speed and acceleration of the palletizing robot. The simulation results showed that, the curve fitted by the quintic polynomial trajectory planning method was smoother and such method ensured no sudden change in the speed and acceleration, which assured that the motion process of the palletizing robot was more stable and smoother. Such trajectory planning method can ensure that the palletizing robot achieves the smooth transition of the speed and acceleration according to the predetermined trajectory, and it has improved the motion accuracy of the palletizing robot.