Abstract: A harden coating of Fe-Cr based alloy, containing high boron, was produced on midium carbon steel plate by plasma cladding process. The phases, microstructures and microhardness of the cladding coating were investigated by Scanning Electron Microscopy (SEM), X-ray Diffractometer (XRD), Energy-dispersive Spectroscopy (EDS) and microhardness tester. The chief phases of the cladding coating are γ-Fe(Ni) and Fe₂B. The microstructures of cladding coating were consisted of Fe₂B with shapes of equilateral L or lath and eutectic of γ-Fe(Ni) and borides, and the eutectic presented itself with lamella or rosette shape. An excellent metallurgical interface between the coating and the substrate appeared. The microstructures of the layer near the interface exhibit fan-shaped or dendritic structure. The microhardness value of the cladding coating was 1 100-1 400HV0.2 and was about 4 times of the substrate (290HV0.2). The microhardness of the substrate near the interface increased to 600HV0.2 because of quenching.