Abstract: The fly ash paste filling mining is one of the most effective mining technologies to control the overlying strata failure. Based on the actual situation of Xingtai mining area, a numerical model was established, the influence degree of the two main filling parameters on the control of overburden rock was numerically studied in terms of filling strength and filling rate, the influence of the two on the surface subsidence was also analyzed. The results showed that the filling strength plays an important role in the maximum subsidence of the surface, it is an important prerequisite to ensure that the filling rate is high enough to achieve the desired effect, the maximum surface subsidence increases linearly with the decrease of the intensity when the filling strength is 1.5 MPa to 3.0 MPa. The maximum surface subsidence increases rapidly when the filling strength is less than 1.5 MPa. The filling rate decreases and the surface subsidence increases gradually, and the amplitude of change is basically uniform.