Aiming at the surface subsidence prediction assessment in the mining areas,this paper took the secondary rigidity and gentle coal layer for an example,and analyzed the stability of probability function model.The result indicates that the model has a good stability,and satisfies the precision demands for prediction assessment.Thus,we can use it in surface subsidence prediction of the secondary rigidity and gentle coal layer.Among the coal stratum angel,thickness,depth and the synthetic evaluation factor,the sensitivity of the synthetic evaluation factor is the greatest,and the factor is the main control parameter.