Digital image processing technique is used to analyze the high strength alloy steel corrosion samples acquired from accelerated salt spray corrosion test. A method of analyzing the corrosion feature based on various color spaces is provided. The proper color component is selected to extract the corrosion feature by analyzing various color spaces of corrosion images such as RGB, HSV, YCbCr and their statistics information. Combined with the theory of corrosion generation, the data of color channels are processed and the feature of metal material salt spray corrosion is recognized. Through processing several sample color images of alloy steel, it is proved that the feature extracted by this procedure has better accuracy and the corrosion degree is quantifiable and the precision of discriminating the corrosion is improved.