Abstract: WC-10Co-4Cr coatings were sprayed by high velocity oxygen fuel on the surface of Q235 steel, and orthogonal experimental design was used to analyze the effects of the spray parameters including spray distance, oxygen and kerosene flow rates on the porosity and microhardness of the sprayed coating. The results show that oxygen flow rate played the most important role on the porosity and microhardness of the coating, while the spray distance and kerosene flow rate had less effect on the properties of the coating. At the optimized spray parameters as following: oxygen flow rate 897 L·min-1, kerosene flow rate 0.38 L·min-1and spray distance 300 mm, the porosity of the coating was 0.31%, and the microhardness was 1 323 HV.