The Northern marginal fault of Xinglong Mountain, which is also the southern margin of Lanzhou basin, is one of the most important active fault in Lanzhou area. The fault is about 54 km shows an arc shape with the eastern segment in NW direction and the western segment in EW direction. During the Caledonian and Yanshan Movements, the tectonic stress field in Lanzhou area were mainly a feature of compressive stress with principal direction of NE-SW. The fault keeps a thrust movement from SW to NE. In the Cenozoic era（Himalayan Movement）, the principal stress changed into NNE-SSW, and the activity of fault also changed to the thrust with left-lateral slip on eastern segment and normal with left-lateral slip on the western segment. The latest stage of activities was probably in the Early to Middle Late Pleistocene epoch, corresponding to the formation of Ⅲ terrace of Huanghe river in Lanzhou basin.