Aim at the existing problem of the growth of WC particles in the traditional reduction and carbonization process, adopted the method of carbon-hydrogen coreduction-carbonization to prepare nano-level powders and studied the effects of the n(C)/n(W) of precursors and reaction temperature on the properties of WC. The results show that the carbon content of WC is related to the n(C)/n(W) of precursors, and the optimum molar ratio is 3.6. The average particle size of WC is closely related to reduction temperature and carbonization temperature duo to the transformation of W to WC has structural heredity. Pressure of water vapor in the system decreases due to the reaction of H2O and C with the reduction temperature increases from 680 ℃ to 800 ℃, and which inhibited the volatilization-deposition growth of W particles in hydrogen reduction process. Therefore, the average particle size of WC decreases with increasing reduction temperature. The high temperature can promote the grain boundary migration of WC particles and the combination growth of nano W particles, and the average particle size of WC increases with increasing carbonization temperature. When the n(C)/n(W) of precursor is 3.6, the average particle size of WC powders is 87.3 nm after reduction and carbonization at 800 ℃ and 1100 ℃, respectively.