The invention provides a device for metal surface cavitation jet flow strengthening. The device comprises a lifting device, a three-dimensional moving device, a control system, a water supply system, a spiral cavitation jet flow nozzle, a processing pool and a recovering pool; and the processing pool is located on the lifting device and is communicated with the recovering pool, the spiral cavitation jet flow nozzle is installed on the three-dimensional moving device and located above the processing pool, the water supply system supplies water to the spiral cavitation jet flow nozzle, and the control system controls the lifting device and the three-dimensional moving device to move according to the set program. According to the device, a spiral accelerated runner is used for enabling liquid media to generate the angular spin rate so as to form a vortex, the vortex center pressure of the vortex is reduced to the saturated vapor pressure even negative pressure, a large number of stable vortex vacuoles are induced to be generated, external energy such as lasers do not need to be introduced to generate cavitation vacuoles, and the cavitation generating effect is straightened through the effect of a diffusion angle of a diffusion cavity of the spiral cavitation jet flow nozzle.