The invention relates to engineering machinery equipment and methods, in particular to a system and method for full-automatic welding of a standard joint of a building hoist. The system comprises a body, a welding system, feeding systems, a handling system, tool systems and discharging systems. Each feeding system comprises a material table, a material table transfer platform and a material table walking rail. The handling system comprises a handling robot, a handling robot transfer platform and a handling robot walking rail. Each tool system comprises a rotary standard joint tool and a component clamping mechanism. The welding system comprises welding robots, a welding robot transfer platform and a welding robot walking rail. Each discharging system comprises a discharging robot, a discharging robot transfer platform and a discharging robot walking rail. The system and method have the beneficial effects that by means of the overall automatic feed, welding and discharging tool robot system, the stability and welding quality of products are improved, the labor production efficiency is improved, the labor intensity of workers is reduced, and the work environment of the workers is improved.