Abstract: To evaluate the stability of buildings foundation above the old goaf,the time- varying laws of parameters of probability- integral method in the decline stage were analyzed; the relationship between the parameters of the surface residual deformation and its geological mining conditions was established according to the field data of the observation stations; finally,the surface residual deformation was gained by calculating the difference of prediction results between the forecasting date and the stabl e state,and the stability assessment conclusion about the old goaf buildings foundation was deduced via comparing the residual deformation with the critical buildings defor mation.The results showed that residual subsidence coefficient and the main influential angle tangent decreased with increasing the mining degree,and the duration of the r esidual subsidence increaseel with increasing the ratio of rock strata and mining thickness. The assessment method took the limit subsidence of the fully activated goaf int 0 account,and the conclusion could meet the requirements of building safety.