The invention discloses a trajectory tracking measurement and control system with a postwelding impact robot. The trajectory tracking measurement and control system is composed of four light reflectors, two reflection type infrared or laser sensors, two distance measuring sensors, a synchronous motor, movable welding equipment, the postwelding impact robot, a measuring bar and two miniature synchronous motors. The way for recording the moving track of the movable welding equipment and the postwelding impact robot in real time is provided and is applied to the trajectory tracking measurement and control system with the postwelding impact robot, and the postwelding impact robot can accurately track the trajectory of a welding nozzle and conduct impact along a welded joint, so that postwelding impact efficiency is improved, and welding quality is enhanced.