Abstract: Western China to study thick loess cover layer of collapsible loess mining impact on mining subsidence, the paper through the loess layer of wet mining subsidence mechanism to study the establishment of a mining collapsible loess layer of surface subsidence caused by the calculation model, and the results apply to mining B40301 Binchang Face validated analysis. The results show that: the wet surface subsidence collapsible loess layer not only directly affected by mining also involves additional working surface deformation produced in collapsible loess; additional surface subsidence value derived from mining caused collapsible loess layer; through field investigation, model estimates and the actual match face to verify the article derive additional surface subsidence value calculation model of collapsible loess layer cause is feasible and practical.