WCu composites were fabricated by infiltrating Cu alloys doped with Zr and Cr into W skeleton in order to strengthen the W/Cu interfaces. The effect of Zr and Cr on the mechanical behaviours including flexural strength and impact toughness, and thermal shock resistance of WCu composites was investigated. The results show that the addition of a small amount of Zr and Cr increase the flexural strength and impact toughness of WCu composites. With the increase of thermal shock temperature, the flexural strength of WCu composites decreases. However, the addition of Zr and Cr in WCu composite can reduce the effect of thermal shock on mechanical behaviours obviously.