The 1Cr15Ni4Mo3 alloy powder is cladded on the surface of 30CrMnSiNi2A ultra-high strength steel by the laser cladding technique. The microstructure and mechanical properties of the cladding layers are investigated. The results show that, the microstructure is mainly the martensite and austenite double-phase structure. For the cladding joints, after the low-temperature tempering at 200 ℃, the tensile strength is larger than 1300 MPa, the extension rate is 8.1%, and the impact toughness is 53.8 J·cm-2. The tensile strength and extension rate reach to 90% of those of 30CrMnSiNi2A ultra-high strength base steel, while the impact toughness is doubled if compared with that of base material.