In order to study the stability of complex goaf and carry out engineering geological survey,RMR classification method and Q system classification method are used to evaluate and classify each part of rock mass,and Flac3D numerical simulation software is used to simulate and predict the formation process and stability of goaf.The classification results show that the quality of the surrounding rock mass of the upper wall and the ore body is good,and the quality of the surrounding rock mass of the lower wall is medium.Through the analysis of stress isoline cloud map,displacement isoline cloud map and plastic zone distribution map,it is concluded that the surrounding rock of goaf No.2 and  No.3  in Scheme 1 has a plastic state because the shear stress is too concentrated and higher than that of the rock mass itself,the maximum displacement appears in the roof of No.2 goaf,and the maximum horizontal displacement appears in the center of the top and bottom of the goaf and has a tendency of connection.Although the plastic zone in Scheme 2 is not connected,the existing plastic zone will impose certain potential safety hazard on the stability of the goaf.