Abstract: Taking the broken rock mass in goaf as the main research object, the influence factors of goaf activation are analyzed through theoretical analysis, and the main activation factors under specific engineering conditions are determined as water filling, building load. The numerical simulation scheme is designed for the control factors of the water filling or not and the building load. Based on the monitoring information of surface movement and deformation, the laws of surface movement and deformation under different working conditions are obtained and the water can promote the deformation of broken rock mass. Through gradient loading of 4^# coal and 9^# coal according to the construction load of 0.015 MPa and 0.1 MPa per floor, the simulation results show that the overlying rock foundation of 4^# coal mined-out area is allowed to apply load of 0.045 MPa, the influence depth is 19 m, which does not meet the requirements of building foundation construction, so it is necessary to reinforce the 4^# coal mined-out area; the allowable load is 2 MPa of 9^# coal mined-out area overlying rock foundation, and the foundation disturbance depth is 70 m, which meets the design requirements.