Abstract: The effect of process parameters on the (Cr,Fe)₇C₃/γ-Fe ceramal composite coating formed by plasma surface metallurgy on Q235 steel substrate was researched.With the increase of scanning speed or decrease of working current, microstructure of coating was refined.Therefore, it can be ascertained that the optimum working current is 300 A and the optimum scanning speed is 500 mm/min.A in situ reinforcing phase (Cr,Fe)₇C₃ ceramal composite coating was fabricated on substrate of Q235 steel by plasma surface metallurgy with the Fe -Cr -C -Nb -Al alloy powders. The ceramal composite coating has a rapidly solidified microstructure consisted of primary (Cr,Fe)₇C₃ and the (Cr,Fe)₇C₃/γ-Fe eutectics, and is metallurgically bonded to Q235 steel substrate.