The invention provides group control device and method for a multi-robot welding system. The device mainly comprises a positioning machine, a PLC electric cabinet, a plurality of welding robots, a welding machine and other parts; the system in on the basis of a communication model of a CC-LINK field bus, the PLC is treated as a working main station, all robots are equipped with CC-LINK communication cards to be used as secondary stations, and the main station and the secondary stations are equipped with detailed control signal sheets for realizing main-secondary information sharing and real-time feedback; in case of a specific complex component, the working area of each robot can be reasonably divided, the quantity of robots for welding can be flexibly selected, a touch screen is operated for human-computer interaction, and therefore, the states and parameter settings of each robot, welding machine, positioning machine and other devices can be monitored conveniently, and as a result, the whole system can be simply, safely, flexibly and efficiently controlled.