The invention discloses a cooperative control system for multiple welding robots based on an improved particle swarm algorithm, and relates to the technical field of automatic welding control over robots. The cooperative control system comprises a PC with cooperative control software installed and the multiple welding robots. Each welding robot comprises a manipulator for welding and a robot control cabinet used for driving the manipulator to work, wherein the manipulator is provided with a manipulator sensor used for sensing the position of the manipulator. The output end of the PC is connected with the robot control cabinet of each welding robot through the Ethernet. The manipulator sensor of each welding robot is connected with the corresponding robot control cabinet through a signal cable and further connected with the input end of the PC through the Ethernet. The welding robots adopt a double-closed-loop control strategy, and the welding motions and positions of the manipulators are fed back to a welding robot controller and the PC simultaneously through the sensors, so that the correctness of position information and the best welding route planning control are realized.