The VC-VB-B4C complex particulate reinforced Ni-based composite coating has been successfully synthesized in situ by prior pasting laser cladding on steel A3. The microstructural and metallographic analyses were carried out by a scanning electron microscopy, energy-dispersive spectroscopy(EDS) and X-ray diffractometer(XRD). The microhardness and wear resistance of the coatings were also tested. The results indicate that the composite coating is bonded metallurgically to the substrate. The microstructure in the bottom of coating consists mainly of oriented dendrites of γ(Ni). The microstructure locating in the center and upper zones contain a large number of VC-VB-B4C complex particles and acicular Cr3C2 phases distributed uniformly in the matrix of γ(Ni) solid solution. The VC-VB-B4C particulate reinforced composite coating gives a high average hardness of HV0.31350 and better wear resistance. The wear mass loss of the composite is just one third of that of the pure Ni60 coating. This could be attributed to the presence of the high content of in-situ synthesized VC-VB-B4C complex particulates and their well distribution in the composite coatings.