Objective To investigate the effect of silane treatment on the binding force and corrosion resistance of E-coating. Methods Cathode electrophoresis was applied to prepare protective coating on rare earth magnesium alloy EW75M. Corrosion resistance was evaluated by electrochemical impedance. The swelling characteristics of E-coating on magnesium alloy substrate was evaluated by NMP test. Scanning Electron Microscope ( SEM) was applied to analyze the coating corrosion microstructure and the interface bonding of coatings. Results The results showed that a transparent and thin film formed on the surface of magnesium alloy treated by silane. The film could protect magnesium alloy from corrosion. Silane film could reduce the occurrence of pinhole and orange peel on E-coating, and increase the density of E-coating. The adhesion and resistance of E-coating were improved by silane pre-treatment on Mg alloys. The silane + E-coating was intact after 102 h immersion in NMP solution, while the E-coating completely fell off after 7 min immersion. In addition, the resistance value of silane+ E-coating at low frequency remained above 10 ^{after 227 h immersion in 3. 5% NaCl solution, which indicated that the E-coating had excellent corrosion resistance. The resistance value of silane+ E-coat was about 4 orders of magnitude of E-coat. Conclusion Silane cathodic electrodeposition composite coating has good corrosion resistance and resistance to swelling properties, and is worthy of popularization and application for the future.}