_{:The WC-12Co composite powder was synthesized by reduction and carburization reactions. With adding various contents of combined grain growth inhibitors (GGI) VC and Cr3C2 into theWC-12Co compositepowder, the effects of the GGI addition on the phase constitution, microstructure and mechanical properties of the coating havebeen investigated by X-ray diffraction (XRD)and scanning electron microscopy (SEM)respectively. The result shows thatthat with the content of GGI increasing in the composite powder, the abnormal grain growth disappears and homogeneous ultrafine grain structure forms, the coefficient of friction of the coating reduces. When the total amount of inhibitor is added in combination 1.0wt.%, the maximum hardness of WC-12Co coating is 1367 HV0.3, and the wear rate of the coating isthe lowest.Further increasing the content of inhibitor, the wear rate of the coating increases, the hardness and the wear resistanceof the coatingdecreases.}