Nanocrystalline layer of a certain thickness has been prepared on the surface of tungsten copper alloy by a supersonic fine particles bombarding (SFPB) method. The micro-hardness and electrical properties were measured and then their phases as well as microstructure were analyzed by XRD and SEM, respectively. The results show that the continuous bombardment on the surface of tungsten copper alloy leading by high kinetic energy of particles during SFPB makes the W particles and copper phase broken and refined. Finally a nano layer has been prepared on the surface of CuW70, whose grain size is about 80 nm and the thickness is about a dozen microns. And the optimum effect is in the subsurface. Micro-hardnesses of the sample’s nano layer significantly increase by about 40%~60% while the conductivity decreases slightly. The formation of the arc can be inhibited and extinguished rapidly for achieving the arc erosion resistance