Abstract: In response to the issue of the impact of mining on the stability of the underlying roadway in the 33 and 32 working faces of Daizhuang Coal Industry, based on the equivalent mining height theory combined with the slip line field theory, the maximum depth of damage to the bottom plate of the backfill mining was analyzed. The development characteristics of the bottom plate cracks during the backfill mining process were detected by drilling observation. Based on the spatial relationship between the backfill and the underlying roadway, a FLAC^3D numerical calculation model was established to compare and study the deformation characteristics and crack development and expansion of the overlying rock during caving and backfill mining, and evaluate the degree of impact of backfill mining on the stability of the underlying roadway. Research shows that the depth of rock damage in the bottom layer of the backfill mining is about 3.5m, which is much smaller than the closest distance of 28.8 m between the backfill and the underlying roadway; The working face adopts the caving method for mining, and the stress on the roof and floor of the mining area is released. The stress reduction area is widely spread to the underlying roadway, and the plastic zone of the floor penetrates the underlying roadway, causing significant deformation of the surrounding rock of the roadway; Using paste filling mining, the stress reduction zone of the top and bottom plates did not affect the underlying roadway, and the plastic zone of the bottom plate was not connected to the underlying roadway. Compared with caving mining, the deformation of the surrounding rock of the underlying roadway was reduced by about 60%. Paste filling mining on working face 33 and 32 had no impact on the underlying roadway.