Abstract: An attempt has been made by the authors to process landsat images using the computer. Through studies, the ratio stretched images and their complemen- tary images have been considered to be a good processing means for interpreting and studying the active fractures in Yunnan province. The processed mosaic maps show well-defined tones and a clear-cut structural framework of the whole province. Onthe basis of the interpretation, some new ideas have been put forwards. regarding the structural division of the province. In the province, there occur NW-,N-S-,NE-and E-W-trending structural zones and two vortex structures of these, the NW- and N-S-trending structural zones, great in scale and having far-reaching influences, control the topography, geomorphology and distribution of the drainage system, lakes and basins.They are still active at present, and earthquakes happenfrequently there. So they are the main fracture zones that merit further work and study. Earthquakes of magnitude≥5 in Yunnan province have also been analysed and studied in a rough way.It is considered that these earthquakes were all tectonic earthquakes except those in the Tengchong area which were volcanic earthquakes. The zonation of earthquakes and the coincidence or parallelism of the long axis of the isointensity lines to the fractures may account for this point.So to study the active fractures and their earthquake-controlling effects is our task in the future. The authors have carried out the work of processing Landsat photos using the reproduction of the ground digital tapes produced by the multispectral scanner installed in the U.S.Landsat.A total of 23 1:1, 000,O00-scale images within the territory of Yunnan have been processed. The fault structure in Yunnan province has been interpreted, and the northwestern part of the work area, i.e.the Jianchuan-Dukou area, has been studied in more detail.