Abstract: Based on the data of field investigations,interpretations of both Landsat images and air photos,seismicity and focal mechanism,this paper describes the neotectonic features of the Ganzi-Yushu fault zone in western Sichuan.The relationship between the forming of pull-apart basins and the occurring of strong earthquakes is also discussed here.The result shows that this fault zone is another large strike-slip fault zone in western Sichuan,which formed and developed from Mesozoic era.It has been dominated by intensive left-lateral dislocation,its maximum horizontal offset is up to about 100 m and the ratio of horizontal offset to vertical offset is about 10 :1 since the Late Quaternary period.Up to 1984,the earthquake eneigy of this fault zone had been so accu-mlated as to cause an earthquake of magnitude 7.4.Therefore,on the basis of historical earthquake activity,it is inferred that this fault zone would enter into a new active period of earth-quake activity with the risk of occurring of an earthquake of magnitude 7 or greater in the next 20-30 years.