Based on the research of loess being of the property of seismic subsidence, this paper pointed out a type of particular disaster that people has not pay attention to, yet, which is that serious accidents of ground losing efficacy will happen in cities on loess sites under the effct of earthquakes. Because of seimic subidence occurring suddenly and distributing inhomogenously generally,the seismic damage of common industrial civil buildings become more serious under the effct of shaking and residual deformation of ground together. Usual phenomena of the seismic damage are cracking, slopping and Collapsing of buildings. To take Lanzhou as an example, the disaster induced by loess seismic subsidence are proved to be serious disaster which can not be underestimated. The engineering field and the department of city construction Should think highly of it, studying the effect of loess seismic subsidence on buildings,taking appropriate prevention measures and lessening or avoiding the loss caused by the disaster of seismic subsidence.