In order to fabricate highly dense W/Cu20 (mass fraction, similarly hereinafter) composite materials, two kinds of tungsten powder with different particle size, A and B, were used. The W powder with different ratios of A and B were directly mixed with copper powder and W/Cu20 mixed powder was obtained. Almost fully dense W-Cu composite materials were fabricated by solid-state hot pressing. The observation of microstructure shows that with increasing of the fine W powder (B) content, the pores formed by the coarse W powder (A) decrease and the pores by the fine W powder increase gradually. Rather dense microstructure is obtained when the W particle distribution is 80%A+20%B. The W/Cu20 with 98.6% relative density is obtained under the processing conditions of sintering temperature of 1060 °C, pressure of 85 MPa and holding time of 3 h. Copper forms into a network structure around the coarse W particles and the fine W particles.