In this paper, the effect of Cu content on the properties and microstructure of W-Cu composites produced by hot extrusion with steel cup and heat treatment was investigated. W-Cu products were sintered at 1150 degrees C under vacuum conditions for 1 h and then the sintered billets were hot extruded with steel cup at 950 degrees C with extrusion ratio 10.56. After heat treatment, W-Cu composites with highly comprehensive properties will be acquired. Metallographic microscopy and scanning electron microscope were used to observe microstructure. Experimental results showed that when the Cu content (10-20 mass%), a little deformation was observed in W phase. When the percentage composition of Cu is high (30-40 mass%), little deformation appeared in W phase, while main deformation occurred in Cu phase. Tungsten phase contiguity in extruded composites is increasing with the decreasing of Cu content. It is hard to achieve the full densification for W-Cu composite with low Cu content (below 20 wt.% Cu) by plasticity deformation technology with small deformation amount. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.