The operation efficiency of the parallel robot on the automatic packing line was optimized under the condition that the stability was not changed. Six key points were established to study the efficiency of the trajectory space planning; the trajectory planning method with the execution time optimization was proposed based on the Delta3 parallel robot.The optimal time was obtained by particle swarm optimization, and it was verified by experiments.The experimental results show that the time needed for the optimized one motion cycle is reduced by 0.104 s, and the curve efficiency is higher; with the increase of time,the impact degree decreases nonlinearly; the packing efficiency can be improved effectively by using the optimized method.This method can provide theoretical reference for other robots trajectory planning research to