WC-Ni-Cr composite cladding is fabricated on the Q235 steel by infiltration brazed in a vacuum furnace. Microstructure of interface and welding specimen's longitudinal section of alloy coating are investigated by CMM-88E metallographic microscope and FEI Quanta200 scanning electron microscope. Element diffusion and distribution along the longitudinal section are tested by the Energy Disperse Spectroscopy (EDS), produced by Oxford Corporation; Influencing factors of the coating's brazed interface are analyzed. The results show that when nickel base coating powders are used for infiltration brazed, the BNi-2 solder is appropriate and the appropriate temperature should be in 1120~1140 °C. The welding interface of vacuum brazing compact very well and the existence of element diffusing forms the metallurgy welding contact surface.