The work aims to study the effect of Si content on the structure, phase, microhardness and corrosion resistance of CoCrFeNi high-entropy alloy coating. In the study, CoCrFeNiSix (x=0.0, 0.5, 1.0, 1.5, 2.0) high-entropy alloy coating on 45 steel substrate is prepared by laser cladding technology, and the phase composition, microstructure, microhardness,corrosion resistance and corrosion morphology of the coating is analyzed by using scanning electron microscope, X-ray diffractometer, micro hardness tester,electrochemical workstation. Theoretical analysis combined with experimental verification shows that the CoCrFeNi high-entropy alloy coating is a single fcc phase. The microstructure of the coating is dominated by equiaxed crystals and dendrites. When the Si content is small, the Si element is mainly segregated in the grain boundaries. As the Si content increases, too much Si will be dissolved into the crystal grains. The average microhardness of the coating increases with the increase of Si content, and CoCrFeNiSi2.0 can reach 566.5HV0.5. In 3.5% NaCl solution, the corrosion potential of the coating increases with the increase of Si content, the corrosion potential of CoCrFeNiSi2.0 is positively shifted by about 160 mV compared with CoCrFeNiSi0.0, and the corrosion current density decreases from 1.17×10–6 A/cm2 to 6.06×10–7 A/cm2, the corrosion resistance is improved. When the Si content is low, continuous large-area corrosion marks appear on the coating surface. As the Si content increases, the surface corrosion is dominated by pitting corrosion. As a result, the addition of Si element to the CoCrFeNi series high-entropy alloy coating can promote the formation of bcc phase, increase the microhardness of the coating, and can effectively inhibit the corrosion tendency of the alloy coating and slow down the corrosion rate of the alloy coating, thereby improving the corrosion resistance.