Silane treatment is an effective method of chemical conversion as a replacement for chromium treatments. In this paper, KH-550 silane treatment was adopted to improve the corrosion resistance AZ31 magnesium alloy. Hydrolysis process of KH-550 in the silane solutions was detected by the conductivity detection method. It was found that KH-550 silane could be hydrolyzed easily and its hydrolysis time was about 10 minutes. Polarization curve and salt immersion were carried out to investigate the corrosion behavior of the coated magnesium alloy treated by five kinds of silane solutions with different silane concentrations. When the concentration of KH-550 in the silane solution was 8%, the coated specimens by heating at 100°C for half an hour after the surfaces dry had more excellent corrosion resistance than others. It was shown that the KH-550 silane treatment could form a -Si-O-M covalent bonded film/metal interface and -Si-O-Si siloxane chains to improve the corrosion resistance of coated magnesium alloy.