Welding robots are widely used in the field of automobile manufacturing. They can not only improve welding accuracy and efficiency, but also reduce labor costs. In the process of automobile body production, there are as many as 4000 ~ 6000 solder joints. Reasonable welding sequence is of great help to improve production efficiency. Therefore, it is extremely important to study the path planning problem of welding robot. A reasonable path helps to optimize the process of the production line, improve the production efficiency of the workstation, and improve the efficiency of engineering design. At the same time, it provides an important theoretical reference for robot trajectory debugging and simplifies the complicated and cumbersome teaching work. In this paper, particle swarm optimization (PSO) algorithm is used to solve the path planning problem of single robot. The corresponding trajectory is generated by establishing mathematical model and calling algorithm. Finally, the effectiveness of the algorithm is verified by a series of experiments and simulations.