After a mine production transfers from the shallow part to the deep,the whole technical adjustment and optimization of the mine ventilation system are required.Given the poor effect of the ventilation system in an underground mine after its trial operation of the deep project,through investigation and detection of the current situation of the ventilation system,the paper figures out that there are the problems such as insufficient air volume,blocked air path,high resistance,insufficient capacity of the main fan,and the existence of air leakage,puts forward some debugging and optimization schemes,such as finding and sealing air leakage point,reducing the resistance of parallel return air circuit,optimizing type selection of the main fan,balancing return air circuit resistance of auxiliary fan.Modeling and calculation analysis are carried out using Ventsim software,verifying the feasibility of debugging scheme.The engineering application shows that it can meet the production demand of the deep underground mine ventilation.