Strong ground motions, the direct inducement of all kinds of earthquake disasters, usually cause considerable casualties and property loss through building collapse and earthquake landslides. The M8.5 Haiyuan earthquake of 1920 triggered numerous loess landslides and caused heavy casualties in the loess hilly area at the junction of Xiji and Jingning Counties, 80 km from the epicenter. Based on the analysis of the landslide distribution characteristics in the Haiyuan earthquake high-intensity area, the geological conditions and seismic response characteristics of typical sites in the landslide-concentrated area were studied by field investigation and numerical calculation. It is concluded that the topographical differences and the overburden on both sides of the loess hill lead to different ground-motion amplification effects, which is one of the factors leading to the successive occurrences of landslides on one side of the hill. The topography, geotechnical property, and soil layer structure of the landslide-concentrated area show that the ground motion in this area rapidly changes with local site conditions. The combined action of stratigraphic site effect and topographic site effect intensifies the ground-motion amplification of the slope surface and increases the seismic force of triggering landslides.