The Al?15Si?xNb coating was used as the research object to explore the effect of Nb content on the microstructure and corrosion resistance of the coating. The microstructure of the coating was observed by metallographic microscope, the phase composition of the coating was analyzed by XRD, and the corrosion behavior of the coating in 3.5% NaCl solution was characterized and discussed by electrochemical experimental methods (including open circuit potential, impedance spectrum analysis and polarization curve analysis). The results show that the Al?15Si?xNb coating is mainly composed of α?Al, primary Si and eutectic Si. A small amount of NbAl₃ phase and Nb₅Si₃ phase are formed after Nb element is added to the coating; The addition of Nb promoted heterogeneous nucleation and significantly changed the microstructure distribution of the coating. The microstructure of Al?15Si?10Nb coating has a homogeneous distribution. Uniformly distributed α?Al, primary Si and eutectic Si will form many uniformly distributed corrosion micro?battery. It can promote Al anodic reaction and make the Al₂O₃ oxide film formed on the coating surface more continuous. The polarization curve of Al?15Si?xNb coating has passivation like characteristics. When 10% Nb is used, the self?corrosion potential and pitting potential of the coating are higher, the product film resistance is larger, and the dimensional passivation current density is lower. Therefore, Al?15Si?10Nb coating has better corrosion.