This paper has discussed the similarities and differences between remote sensing and remote sensinggeological mapping in the rocky desertification area and drawn a mathematical analytical conclusion that the determination of the rocky desertification area is equivalent to the determination of the area that satisfies the condition D_R∈ D_C∩ D_V. On such a basis, two schemes for extracting information from remote sensing images of rocky desertification are advanced. One is to extract the information of remote sensing images of the rocky desertification directly from brightness (or gray level) of every pixel based on the frequency characteristics of limestone rocks and the heat characteristic parameters, in which the relevant method used is called pixel analysis method or direct recognition method. The other is to extract the whole graphical information of the outcrop distribution area of limestone rocks indirectly through logical correlation operation between image areas D_C and D_V based on the model of vegetation image frequency and topology, in which the relevant method used is called graphic analysis method or indirect recognition method. The optimum scheme for pseudo-color composition with the Axis of TM6 as the central waveband has been determined through two times of 30×2 tests of pixel analysis method for images in the test area. Through comprehensive interpretation, it is concluded that the expansion of the rocky desertification area in Du'an is related to excessive human activities. This achievement is attributed to the utilization of this scheme to TM image processing in Du'an County in 1991 and 1998.