Abstract: The Baxiehe basin is located in the center of the Linxia tectonic basin in the western part of the Loess Plateau in Gansu Province. On the northern bank of the river, the ancient and new landslides are well developed, one of which is the Nalesi ancient landslide. The slope of the Nalesi landslide was cut to build houses and thus formed a 20 m high surface, which is dangerous. On the basis of field investigation, this paper analyzes the stability of the landslides under natural conditions, extreme rainfall, and seismic conditions, using Discontinuous Layout Optimization (DLO). The stability coefficient is 1.49 under natural condition, 0.95 under extreme torrential rain, and 0.96 under seismic condition. The results show that there is a possibility of instability under adverse conditions. It is suggested that in the design of landslide treatment, comprehensive prevention such as front edge retaining, back edge and slope dredging and drainage should be taken, and professional monitoring should be carried out as soon as possible to protect both the life and property of the residents at the foot of slope and in the Nalesi town as well.