The work aims to propose a time-optimal trajectory planning method for the valve pocket bagging robot based on improved particle swarm optimization algorithm, so as to improve the working efficiency of the robot. Firstly, the joint space angle corresponding to the trajectory of the operating space was solved by the inverse kinematics equation. Then, the joint space trajectory was fitted by 4-3-4 mixed polynomial interpolation method. Finally, the improved particle swarm optimization algorithm was used to optimize the running time of the valve pocket bagging robot under the speed constraints. From the simulation results, the improved particle swarm optimization algorithm could reduce the total running time by 41.66% under the condition of ensuring the smooth running of the valve pocket bagging robot, and realize the time-optimal trajectory planning of the valve pocket bagging robot in joint space. The method can effectively improve the working efficiency of the robot, prolong the service life of the robot, and provide a scientific basis for the stable and reliable operation of the valve pocket bagging robot.