Abstract: As hanging wall ore is located aside the east flood control dam reservoir in a certain iron mine，the surface are not allowed to collapse，in order to guarantee the safety of flood control dam.Therefore the afterwards fill mining method is adopted to exploit the hanging wall ore.Through the finite different method for numerical simulation，the deformation of the surface as well as the settlement of the monitoring stations nearby the flood-control dam are analyzed as the excavation of the no.1，no.2 and no.3 hanging wall ore in different cases.The simulation results showed that after the no.3 hanging wall ore below the flood-control dam is excavated，the surface deformation range increases，and the settlement value of flood-control dam monitoring stations increases dramatically，which may lead to cracks further expanding，and threaten the safety of the flood-control dam，and even result in the geological disasters such as debris flow.It is suggested that all mining activities near the flood-control dam be prohibited.The excavation of the no.2 hanging wall ore should be in strict accordance with the design requirements.

Key words: Hanging wall ore, Filling, Finite element method, Surface deformation, Settlement