Based on the spectral test and analysis of rock samples from the gold-polymetallic mineralized districts of Mangya area, Qinghai Province, this paper has studied the spectral characteristics of the altered rocks and wall rocks related to gold-polymetallic mineralization as well as their spectral differences within the corresponding TM bands. On such a basis, a model is established for quantitative extraction of the remote sensing information on mineralized alterations and, in addition, the information concerning mineralized alteration is extracted by means of TM images.