Abstract: By means of a scanning electron microscope and its accessory X-ray energy spectrometer, corrosion products and the reason of unqualified corrosion resistance of galvanized steel sheet were analyzed. The results showed that insufficient protection of to the galvanized steel sheet after the hot dip process and long exposure in the corrosive environment, which led to the generation of white rust and red rust, were the main reasons for the disqualification of the corrosion resistance of galvanized steel sheet. This quality problem can be solved effectively by some improvement measures.