In recent years, multi-spectral data have been widely used to prospect the source rock or source region of porphyry copper deposits. In this paper, we present a system to extract the information of alteration mineral from multi-spectral data. The system is developed with the Visual C# 2010 and IDL8.0 platform, and is able to process the ASTER multi-spectral data which is a new multiband file after layer stacking. Based on the principal component analysis, the ASTER data is processed automatically in this system. The result shows two components, the classified information of argillic- and phyllic-altered mineral assemblage and propylitization mineral assemblage. Compared with the traditional processes, the system not only lowers the threshold of the application of remote sensing technology, but also improves the work efficiency significantly.