In order to improve the room temperature strength and toughness of W-5Re alloy, SiC was added to form W-5Re-xSiC composites with high performance using vacuum arc melting. The relationship between the SiC content and the microstructure and mechanical properties of W-5Re-xSiC composites was investigated. The results show that the W-5Re-xSiC composites are mainly composed of W(Re) solid solution, W2C and W5Si3. As the SiC content is increased, the grain size of the W(Re) is refined and the contents of brittle intermetallic compounds are increased. The strength and fracture toughness of W-5Re-xSiC composites firstly increase and then decrease. When the SiC content is 1wt%, the strength and fracture toughness of the W-5Re-1SiC composite reach the maximum values of 1859 MPa and 32.87%, respectively, originating from the combination of grain refinement and W5Si3 toughening.