The invention discloses an ultrasonic assistant laser surface washing system and method. The washing system comprises a laser working mechanism, an ultrasonic vibration mechanism, a controller and a working table. The laser working mechanism is used for emitting lasers and washing the surface of a washing sample. The ultrasonic vibration mechanism is used for generating ultrasonic vibration and simultaneously acting on the washing sample with the lasers. The controller comprises a laser control unit and an ultrasonic control unit, wherein the laser control unit is used for controlling the laser working mechanism, and the ultrasonic control unit is used for controlling the ultrasonic vibration mechanism. The working table is used for storing and fixing the washing sample. The washing methodmainly adopts the washing system to conduct washing, the lasers and the ultrasonic vibration act on the surface of the washing sample simultaneously to form a composite washing technology, thus heatgenerated in the laser washing process can be effectively prevented from accumulating on the surface of the sample, the surface is prevented from being too hot, meanwhile, homogenization of distribution of the energy acted on the surface of the sample by laser spots can be facilitated, the homogeneity of the laser washing surface quality is improved, and significant developing meaning is providedfor development of the field of laser washing.