The loess landslides are serious earthquake-induced secondary disasters

which are caused by a strong earthquake with magnitude 8.5 on the Richter scale in Haiyuan 1920.In this area

the loess landslides have special character not only in kind

but also in scale and density.After investigating in field of landslides

researching loess′s micro structure

dividing the loess layer and researching the shape of landslides located in lanni river

the mechanism of loess landslides is summarized in this article as follow.The local unsaturated loess had abundant hole and before the earthquake the ground water rose suddenly

which made hole water pressure increase and loess dead weight rose.Both the earthquake and the waterpower had effect on the loess liquefaction which caused loess landslides finally.All of above are forming mechanism of loess landslides in Xiji Ningxia.