Abstract: In order to improve the corrosion resistance of the surface of 300M ultra-high strength steel, four sets of coating samples with scanning speeds of 5 mm/s, 8 mm/s, 11 mm/s and 14 mm/s were prepared on the surface of 300M steel by laser cladding technology. The specimen was characterized by optical microscope, scanning electron microscope, X-ray diffractometer, EDS energy dispersive spectrometer, microhardness tester, friction and wear machine and electrochemical workstation instrument, respectively, to characterize the macroscopic morphology, microstructure, phase composition, element distribution, hardness properties, friction and wear properties and corrosion resistance of the coating. The results show that after 300M steel is cladded with C276, the corrosion resistance and hardness of the coating are enhanced, but the wear resistance is worse than that of the original substrate, and the coating morphology is affected by the scanning speed. The greater the scanning speed, the flatness tends to be flatter, and the metallic luster is gradually deepened. At the same time, the phase types of the coating did not change significantly under different parameters, and the main phase was Ni-Cr-Co-Mo. Under the parameter of the scanning speed of 8 mm/s, the coating layer having the highest hardness is about 36.2% higher than that of the matrix, and it also has better corrosion resistance and other mechanical properties.