Abstract: The deformating and damaging characteristics of the buildings and ground subsidence areas in a coal mine goaf is taken as a study case in this paper. The methods called investigation and mapping are applied, and the disease characteristics of the buildings and ground in the study area are exposed. Under the further study, the conclusion that the diseases are caused by disorderly coal mining, uneven foundation soil, incompact filling soil, rigid foundation and brick structure form of the upper-structure, rainfall as well as garden irrigation is drawn. Aaccording to the four indexes of building foundation and upper-structure, which are the bearing capacity, structure, settlement and cracks, the safety of the building is evaluated, and the targeted controlling and reinforcing measures are put forward. Under the study and analysis, the solid technical supporting is provided for the protecting and reinforcing existing buildings in the study area.