Abstract: Ni-TiB2 ceramic-metal composite coating is cladded on the surface of 45# steel by CO2 laser melting a precursor mixture of nickel based alloy powder,boron and titanium powders.Microstructure of cladded layer is systematically studied by means of EPMA,TEM and XRD.The results show that the coating mainly consists of γ-Fe,γ-Ni dendrite solid solution and TiB2,TiB particles and a small a mount of Ni4B3.