In order to investigate the effect of laser remelting on the microstructure and properties of diamond/Ni-based composite coatings, diamond/Ni-based composite coatings were prepared on the surface of Q235 by induction heating. The macroscopic morphology, microstructure, elemental distribution and mechanical properties of the coatings before and after remelting were analyzed and compared with those of the laser remelting by using ultra-deep field microscope, laser confocal microscope, scanning electron microscope, energy spectrometer, X-ray diffractometer, hardness tester and abrasive wear tester. The results show that after laser remelting, the average roughness of the surface of the composite coating decreased from 5.58 μm to 4.88 μm. The number of hole defects in the microstructure was significantly reduced, and the carbide aggregates in the microstructure grew up, while the Cr element increased in the enriched layer around the diamond; there was no significant change in the microhardness of the brazing alloy and the abrasion-resistant properties of the coating.