Abstract: Backfilling mining is one of the most effective technical measures to control surface subsidence. At present, there is no effective way to control the subsidence of roof before backfilling; therefore, this paper proposes that the subsidence is not uncontrolled subsidence of the roof before backfilling. Took 7608 backfilling working face of Xingtai Mine as the engineering background, on the basis of elastic foundation beam theory, through utilizing FLAC3D numerical simulation and the similar simulation experiment, the paper performed an oriented research on the influence factors of the uncontrolled subsidence of the roof before backfilling, and obtained a conclusion that buried depth of coal seam and roof lithology of geological conditions have a great effect on subsidence. In the meantime, appropriately rise the resistance of hydraulic support could play a role in the uncontrolled subsidence of the roof before backfilling. Besides, it could enrich improve and perfect the theory of surface subsidence