The work aims to improve corrosion resistance of steel surface. TEOS-modified silane film was prepared on 40Cr steel surface using silane solution containing tetraethoxysilane (TEOS). Optimal process parameters of TEOS-modified silane film were selected in orthogonal testing method. Film forming property and corrosion resistance of the TEOS-modified silane film were tested by means of scanning electron microscope (SEM), neutral salt spray test, and in electrochemical impedance and polarization method. Copper sulfate corrosion resistance time of TEOS-modified silane film increased by nearly 50% compared with that of silane film. Corrosion potential of TEOS-modified silane films shifted positively in the electrochemical polarization test. Cathode current density decreased sharply to 1.883×10?6 A/cm2. In the electrochemical impedance test, impedance-frequency Bode figure showed that impedance value of complex silane film in low and medium frequency range was higher than that of silane film, indicating that the former exhibited excellent corrosion resistance. Phase angle-frequency figure showed that a wide flat zone of TEOS-modified silane film was present in medium-high frequency range, and its phase angle exceeded that of silane film in medium-high frequency range, showing that the film exhibited excellent condensance property and silane film could significantly improve corrosion resistance of 40Cr. The TEOS-modified silane with compact and dense structure exhibits excellent film forming property and can improve corrosion resistance of the 40Cr steel.