Abstract: By carefully interpreting the Xizang Landsat imageries, we have discovered a series of active faulting belts and recent basins. Moreover, magmatism and volcanic and geo thermal activities may come very intensive in Xizang. We have applied the Landsat image to making the seismo-tectonic map of Xizang. It shows that the Xizang plateau has three main structural types. The south Xizang area consists of many closely parallel and rectilinear lineaments which indicate an intensively compressive deformation; the middle Xizang area presents continually lenticular-like structures which show a plastic deformation; and the Qiangtang plateau possesses conjugated fracture deformation. These properties determine the seismic activities in the Xizang region and the three seismic areas can be classified.There have been more than 284 earthquakes with magnitude above 5 since 1870. We have subdivided the seismic events occuring during 20 th century into three periods, each extending about 30 years. Now the third period is going to come to an end.Finally we point out that earthquake frequency and intensity in Xizang are related to the collision of the India-Eurasia plate.