Abstract: The filling mining method of the underground point column changes the original stress state of overlying strata，which may lead to the surface distortion and movement of rock layer. Then，safe use and protection problems of 3# large ditch waste rock field will he affected. In order to ensure the stability of the surface waste rockfill，the finite difference program FLAC3 D was used to simulate the effect of underground orebody mining on the surface waste rockfill.  The simulation results show that the movement of strata is a dynamic process from bottom to top，and the subsidence deformation of the surface waste rock is only 3. 8 cm，and the surface does not produce plastic disturbance zone，which illustrates 3# ditch waste rock field is in a safe and stable state. The results provide guidance for the design and construction of 3# large ditch waste rock field.

Key words: underground mining, dump, stability, surface, point pillar