Abstract: In order to explore the influence of the seepage of the leftover water sump in the open pit on the mining stability of the mine roadway after the coal mine is converted from open pit mining to underground mining, taking Pingzhuang West Open pit Mine in Inner Mongolia as the research background, the two wing water silos and mine workings are modeled by using FLAC numerical simulation software. On this basis, the points for attention and improvement measures in the mining process of the two wing roadway are proposed. The numerical results show that the maximum plastic pressure of the roadway is concentrated at the bottom of the roadway under two working conditions; the displacement deformation plastic zone is not connected, and the tunnel has no overall plastic connection failure and water permeability failure under the influence of seepage; under the condition of extreme water level, the seepage flow at the bottom of both wings of the roadway increases obviously, but the maximum seepage flow meets the specification requirements; due to the time effect, the strength of the surrounding rock of the roadway decreases and long-term creep deformation will occur at the same time. Therefore, waterproof and drainage measures should be taken for the pit bottom and pool.