The Menyuan area of the Qinghai Province lies to the northern foot of the Qilian Mountain, three times of earthquake took place from August through September of 1986, the strongest of which is magnitude 6.4 (on the Richter scale). Remote sensing technology played an important role in the investigation of geological background and damage caused by earthquake. By the interpretation of satellite images and aerophotos produced before and after the earthquake, it is found that Menyuan earthquake is on the connected zone between Qilian Mountain and the Hexi Corridor. The well-developed fault structures, distributed mainly in the northwest direction, control the formation of intermontane basins and valley basins, and are very active in the period of new structure movement, such as the Quaternary strata are fractured; the geomorphological difference is clear; the drainage system and ridges are deformed; the proluvial fans are folded and displaced. Remote sensing images show the earthquake bulges and earth crevices clearly. Analysing these images and combining with geological and earthquake information, it is found that a new structure activity is strong in this area, especially the fault activities at the northern foot of Qilian Mountain. Some major earthquakes such as Haiyuan, Gulang and Changna took place in the past on this active zone, and there were more minor earthquakes also It is Considered that the northwest fault at the northern foot of Qilian Mountain is an earthquake source and has close relation with Menyuan earthquake. On the middle and east part of this fault, some strong and moderate earthquake will take place in the future.