Abstract: In order to better understand the change characteristics of mined out area breakdown, we study the expansion law and calculation method of subsidence volume in goaf. In the same and different geological conditions, increasing the mining area according to the interval of 10%, we predict the value of surface movement and deformation. Through analyzing multi-group experimental results, we obtain that mining area and subsidence volume has a linear positive correlation, meanwhile, we deduce the calculation method of goaf subsidence volume. The results show that the same mining area will produce the same subsidence volume in the same geological conditions. We also present a new method for calculating subsidence volume by mining area S and subsidence coefficient q, and verify that the method has good applicability.