Abstract: SiC nano-medium is adopted to the HS-WEDM Test of Cr12MoV Die Steel and the machining effects are compared with the conventional medium in order to improve the cutting speed, improve the machining surface quality and reduce the electrode wire loss. The research shows that the cutting speed of SiC nano-medium is increased by 22.16%, the surface roughness of SiC nano-medium is reduced by 15.05% and the reduction of electrode wire of SiC nano-medium is reduced by 21.87% under the processing conditions of pulse width 45 μs, pulse interval 200 μs, peak current 25 A and mixed powder concentration 0.3 g/L. The intervention of nanoparticles improves the discharge conditions between the electrodes and increases the machining stability and the cutting speed through enlarging discharging-gap. At the same time, the intervention of nanoparticle improves the surface processing quality and reduces the wire electrode wear through increasing the spark discharge channel between the electrodes and dispersing the discharging points.