The analysis of the characteristics of rocks and minerals constitutes the physical foundation of remote sensing exploration and rock recognition. In order to understand the spectral features more completely, the authors tested five different igneous rock samples from Xinchang area and analyzed their emission spectra. On the basis of emission characteristics of normal minerals and radicals, the authors analyzed the curves and obtained the location, depth, width, depth/width ratio, area and symmetry of the low emission bands by using the continuum removal method. The relationship of composition, alteration characteristics and associations of minerals to remote sensing spectral characteristics as well as its formation mechanism are also discussed in this paper.