With mining downwards, it is an important problem facing Jinchuan Longshou Mine whether the upper filling body can meet require of mining the lower ore. According to the actual condition in Jinchuan Longshou Mine, using three - dimensional numerical simulation, this paper analyzes the stresses, displacements and safety factors of mined - out area and filling body under the conditions of different filling height of down hexagon drift, and the drew conclusions provide theoretic guidance for safety mining.