A phosphate–silane surface treatment is developed to improve the corrosion resistance of phosphated magnesium AZ31 by dihydric phosphate solution. Silane KH560 solution is selected to treat the phosphated magnesium AZ31 alloys. The morphology, thickness and composition of the coating and the corrosion resistance of the coated samples are studied by scanning electron microscopy (SEM), XPS analyses and corrosion tests (including hydrogen evolution detection and EIS). An about 2μm silane coating consisting of SiOSi and SiOMg bonds is formed on the surface of the phosphated magnesium alloys. The silane coating apparently improves the corrosion resistance, adhesive bonded performance and durability in hot-humid environment of the phosphated magnesium AZ31 alloys by means of increasing the polarization resistance R pCP in NaCl solution, initial bond strength and residual bond strength of adhesive-bonded joints in hot-humid environment. The improvement of silane pretreatment on the corrosion resistance and adhesive-bonded performance of phosphated Mg AZ31 is attributed to the improvement of SiOSi bonds in silane coating on the intermolecular interaction between the adhesive and phosphate coating and sealing effect of silane coating to the micro pores in phosphate coating.