The invention discloses a metal crystallizer adopting ultrasonic wave cavitation reinforcement and a cooling method thereof, which are used for the technical fields of continuous casting crystallization, and the like of steel and nonferrous metal. The metal crystallizer comprises a crystallizer, an ultrasonic wave signal generator and an energy converter, wherein the energy converter is installedon a shell of the crystallizer, and the ultrasonic wave signal generator is connected with the energy converter by a lead. The invention transmits a high-frequency signal by the ultrasonic wave signal generator to lead the energy converter to generate ultrasonic wave vibration and generate the ultrasonic wave cavitation effect on cooled water in the crystallizer, and the liquid is changed into a superturbulent flow state and reinforced to exchange heat. The invention improves the cooling performance and the mechanical performance of crystallized metal, automatically prevents scale, reduces the crystallizer structure, saves energy and has long-term high-cooling efficiency.