A three-dimensional synchronous loading device for ultrasonic-assisted laser melting deposition molding of large-volume parts relates to a three-dimensional synchronous loading device for ultrasonic-assisted laser melting deposition molding. The device consists of slide rail substrate, deposition substrate, bottom plate, support column, ultrasonic vibrator, inner annular track, outer annular track, wedge base, fixed plate, circumferential drive motor, lift drive motor, radial drive motor, radial drive pulley, The first toothed belt, the radial drive motor base, the guide groove, the driving pulley, the driven pulley, the second toothed belt, the moving wheel and the moving wheel fixing frame are formed. The invention realizes the real-time loading of the auxiliary ultrasonic field in the process of forming large-volume parts by laser melting deposition, and solves the problem of easy formation of directional structure in the parts and the problems of large residual stress in the parts when forming large-volume parts by laser melting deposition. The present invention is suitable for laser melting deposition of parts.