The Cr3C2-CrB reinforced Ni-based composite coating is successfully in situ synthesized by laser cladding on steel A3 substrate by prior pasting. The microstructural and metallographic analyses are performed by metallurgical microscope,scanning electron microscope(SEM), energy-dispersive spectrometer(EDS), and X-ray diffractometer(XRD). The microhardness and wear-resistance of the coatings are investigated. It is indicated that a smooth and in situ synthesized Cr3C2-CrB reinforced composite coating can be achieved employing a proper amount of (B2O3+Cr2O3 +C) doping under suitable processing parameters, and the excellent bonding between the coating and substrate is ensured by the strong metallurgical interface. The bottom of the coating is composed of γ(NiFe) dendrite containing Cr,Fe borides and carbides. In the middle and upper zones of the coating, lots of pre-eutectic Cr3C2 rods are abreast arranged and CrB particles dispread in the Fe2C/γ(NiFe) eutectic matrix. Because of the presence of Cr3C2–CrB reinforcements and their homogeneous distribution, the composite coating gives the high average hardness of HV0.31100 and better wear resistance. The wear mass loss of the composite coating is just one third of that of the pure Ni60 coating.