Powder particle size is the key factor that affects wear resistance coating. The effect of WC granularity on the microstructure and properties of WC-Ni brazing coatings was studied. Three WC-Ni wear-resistant coatings with different WC sizes were prepared by flame brazing technology. The microstructure and properties of the coating were analyzed by scanning electron microscope,energy spectrometer,microhardness tester and rockwell hardness tester. The results show that:With the increase of WC particle size,the metallurgical reaction degree of Ni solder and WC enhanced phase decreased. When WC particle size is 18 ,2,3 μm,long strip Ni W phase appears in the overlayer of coating interface. When the WC particle size is 250,3,80 μm,the rockwell hardness of the coating is the highest,and the coating has the best wear resistance.