The invention relates to a metal part compound manufacturing system and method combining ultrasonic processing and material adding and material reducing. The metal part compound manufacturing system comprises a material adding printing unit, a material reducing cutting unit, an ultrasonic surface processing unit, a system switching unit, a multi-degree-of-freedom worktable and a controlling unit;the material adding printing unit, the material reducing cutting unit and the ultrasonic surface processing unit are mounted on the system switching unit, and the system switching unit can be controlled to switch the material adding printing unit, the material reducing cutting unit or the ultrasonic surface processing unit to the position above the multi-degree-of-freedom worktable through the controlling unit. According to the metal part compound manufacturing system and method combining ultrasonic processing and material adding and material reducing, in metal material adding manufacturing, the online ultrasonic surface intensifying technology and the material reducing cutting machining technology are coupled simultaneously, improving the surface smoothness through online material reducing cutting and improving residual stress distribution and refining the microstructure through online ultrasonic surface processing play a role in the material adding process simultaneously, and the problems that material residual stress is large, the surface roughness is high, the forming precision is poor, and the microstructure is uneven are solved.