Abstract: Diamond /Ni-based alloy composite coating was made on the surface of 45 steel by induction brazing process. The hardness and wear resistance of the coating were tested by Rockwell hardness tester and abrasive wear tester, and the morphology of the coating, brazing filler metal and diamond were observed by ultra-depth of field microscopy and scanning electron microscopy, the micro-region compositions on the diamond surface were analyzed by energy dispersive spectroscopy. The micro-morphology, wear laws and mechanisms of the coating were preliminarily studied. The results showed that the diamond is dispersed in the Ni-based alloy composite coating and achieved a good metallurgical bond with the brazing alloy. The increase in the content of diamond particles can significantly improve the hardness and wear resistance of the coating. When the mass fraction is 20%, the macrohardness reached 63 HRC, which was 1.5 times higher than that of the pure brazing coating; under the same wear test conditions, the wear loss of the pure brazing filler metal coating reached 0.335 4 g while the 20% diamond/Ni-based alloy composite coating was 0.097 9 g, which was only 29.2% of the pure brazing filler metal coating.