The large scale of mined-out goafs in Miaoling Gold Mine where many abandoned roadways and goafs yet to be dealt with leads to disturbances of air flow,large volume of air leakage,poor ventilation effect and low operation efficiency of the main fan in underground ventilation.Based on the coupling model of variable weight and variable fuzzy set,the stability risk of the existing complex goafs was evaluated.By backfilling the large scale goafs of high risks and closing the goafs and abandoned roadways of average risks,the phenomenon of air leakage and cross-wind was greatly reduced.The adit on 459 m was added to serve as a new air inlet passage,which optimized the original single-wing diagonal ventilation system into a double-wing one,effectively shortening the ventilation line and improving the air quality.The ventilation network simulation and calculation were conducted based on the Ventsim,the wind pressure required for mechanical ventilation in easy and difficult ventilation periods was calculated.On the basis of fully utilizing the existing fans and adding a small amount of excavation works,the simulation and optimization have effectively improved the air flow quality,ensured the ventilation effect and saved the renovation investment.