This paper introduces a newly developed CuW electrode for high performance electrical discharge machining (EDM). Conventional CuW electrode used widely for high precision EDM is generally made by melting method, and the mixture ratio of Cu and W is restricted within narrow limits. On the other hand, it can be changed extensively in the case of a new CuW electrode made by powder sintering method. In order to obtain the higher metal removal rate with smaller electrode wear rate, the optimum mixture ratio of Cu and W was investigated. Experimental results show that the EDM characteristics such as metal removal rate, electrode wear rate and the surface finish for metal mold steel greatly depend on the mixture ratio of CuW electrode. The electrode wear rate could be reduced by using the new CuW electrode with proper mixture ratios, compared with the conventional one, since workpiece material adhered to the electrode end surface during machining and prevented the electrode from wearing with high temperature. Also, better machining stability and better surface finish could be attained under proper mixture ratios of Cu and W. Therefore, the new CuW electrode made by powder sintering method has high possibility for higher performance EDM.