Nanocomposite Ag/SnO2 coating was prepared on pure Cu-surface by plasma spraying using the Ag-12%SnO2 mixed powder fabricated by chemical coprecipitation and high-energy ball milling. The physical property and electrical property were tested in vacuum the surface structure was observed and analyzed by SEM. The results show that the thicker nanocomposite Ag/SnO2 coating is, the smaller density is, the larger resistivity is, the higher the breakdown strength is. The hardness is related to the distribution of SnO2. The distribution of breakdown strength values is connected with coating surface roughness. The arc of nanocomposite Ag/SnO2 coating is dispersive and the arc erosion rate is low