Abstract: The ETM+ and DEM (digital elevation model) data were used to help extracting information of lithostratigraphic units based on the “digital mapping system” in 1∶250 000 digital regional geological survey of the Minhe County, Linxia City and Dingxi City sheets in the border region of Gansu and Qinghai. The data preparation mainly involves remote sensing and landform information extraction and preprocessing. DEM data were derived from contours of the digital relief map. Other hydrologic and topographic parameters were derived from DEM, for instance, drainage network. After topographic correction, linear enhancement, color elongation, the rate of spatial resolution of remote sensing data was enhanced. Through color synthesis, combined with DEM, the tectono-stratigraphic divisions and recognition of some lithostratigraphic units in the study area were achieved. Practice proves that this work is an important auxiliary means for geological mapping.