The forming and inner surface polishing of workpieces with complex internal cavity structures has always been a problem that troubles the academic community. Complex parts can be formed by metal additive manufacturing technology, but unfused powder remainsand the surface is very rough, which seriously affects the workpieces‘ performance. In this paper, the influence of vibration-assisted magnetic abrasive and polishing parameters on the processing results during polishing is studied for the polishing of irregular waveguide internal surfaces with complex internal cavities formed by selective laser fusion coagulation.