Using digital processing method of remote sensing and GIS, TM images in 1996 are interpreted and the database of the sandy land in Gansu province is established. It includes TM image, graph (scale 1∶100 000) and its attributing database. In order to interpret correctly, the interpreting insignia system of sandy land on TM images has been established through analyzing the relative reference and images and then been corrected in the fields. The definition of the sandy land is covered by sand, the vegetation is lower than 5%, and it includes sand desert. Through the study practice and analyzing of sandy land databases, the following conclusions can be gained: (1) In Gansu province, there is as much as 2 750 863 hm² sandy land occupying 6.054% of the area. And of the 86 county units of the province, there is 32 counties distributed by sandy land. (2) Comparing with traditional methods, there are many advantages using digital processing method to establish the sandy land database such as, mapping rapidly, high accuracy and lower expenses. (3) With the same interpreting insignia and graphical database and attributing database that are well matched with image database, the sandy land can be monitored accurately in large scales.