WC-Cr3C2 cermet coating on carbon steel was fabricated by laser controlled reactive synthesis method. Effect of diluents is the key factor influencing the cladding process. When the amount of diluents is 30%, the reaction becomes steadily and the smooth coating can be achieved. Observations of the microstructure and phase composition of the sample showed that the coating was a complex phase system which consisted of WC and Cr3C2. In order to improve bond strength of the coating, Ni was selected as additive. The interface morphology showed that the bonding between coating and substrate was metallurgical bonding.