The paper deals with the studies on spray electrolyte plasma polishing (SEPP) of the GH3536 superalloy produced by selective laser melting (SLM). The theoretical operation of SEPP is shown. The GH3536 superalloy plate manufactured by SLM is used as the experimental specimen. The regularity of surface roughness on cathode feed velocity is presented. Key parameters, like distance between anode and cathode, voltage, temperature and flow rate of the electrolyte are investigated. The surface roughness, micro morphology and chemical composition of the specimen before and after polishing are detected. SEPP technology is found to decrease the surface roughness from Ra = 13.93 µm to 0.107 µm, and the specimen is smooth and bright without obvious processing traces. The oxides and other impurities on the surface of the specimen are removed, and the contents of Ni, Cr and Fe increase. The SEPP technology proposed in this paper, as a new green and efficient surface finishing technology, has the potential for further development.