MoW coating was prepared by supersonic plasma spraying technology on 45CrNiMoVA steel. The bonding strength of the coating were tested. The electrical conductivity of the coating was tested by resistance tester. The arc erosion test of MoW coating with different discharge current in atmosphere was carried out by using high voltage arc device. The coating structure was analyzed by field emission scanning microscope (SEM) and electron spectrometer (EDS), and the phase composition of the coating was tested by X ray diffractometer. The results show that the MoW coating prepared by the supersonic plasma spraying process has good adhesion with the substrate, and the conductivity is 6.12%IACS. The addition of W improves the chemical defect ratio of coating and leads to the decrease of conductivity. Porosity is one of the main reasons for low conductivity of coating. The oxidation has little influence on the conductivity of MoW coating. As the discharge current increases, the MoW coating arc erosion area increased significantly; the current size of the errosion coating reflects two different errosion morphology; the greater the porosity, surface roughness, arc erosion resistance of the coating performance worse. The arc erosion resistance of MoW coating is better than that of pure Mo coating.