Grey relational method is a data process method used to sort out the correlation extent of influence factors in a system with uncertain information. In this paper, it is applied to evaluate the effect of environmental factors on Atmospheric corrosion of Aluminum alloys and find out the main factors. Analysis results indicate that the influence order of the meteorological factors in atmospheric corrosion exposing for one year, three years, six years and ten years is always the same: Fog﹥RH﹥Humidity over 80%﹥Rain﹥T﹥Precipitation﹥Dew. But for pollutant factors, the sorted result is changeable at different exposure time. The effect of , is obvious all the time, and plays an important role in the initial stage of corrosion, yet is turned to be the dominant factor with increase of the exposure time.