Objective To get a conversion coating with superior anti-corrosion performance. Methods The KH560-KH791-zirconium nitrate composite passivation solution was obtained by means of compositing and hydrolyzing two organic silanes followed by addition of zirconium nitrate. The solution was used on the galvanized sheet and the performances of the conversion coatings formed were comparatively characterized by salt water immersion testing, neutral salt spray testing and adhesion testing with the coatings prepared without adding zirconium nitrate. Results In the 72 h salt water immersion test and neutral salt spray test, the conversion coating prepared with the addition of zirconium nitrate was much better than that prepared without zirconium nitrate addition, and in both cases the adhesion test results reached Level 1. Conclusion the participation of corrosion inhibitor zirconium nitrate may fill the gaps in the coating, resulting in higher resistance to penetration of corrosive medium and further improvement of the anti-corrosion performance of the passivated coating.