Abstract: In view of status of serious exterior ventilation leakage of auxiliary inclined air returning shaft used for staff and material transportation in Fengchishan Coal Mine, wind meter direct measuring method was used to test mine exterior ventilation leakage of selected test points, winch rope access window of explosion-proof ventilation door was determined as main ventilation leakage source according to change of exterior ventilation leakage rate. In view of problem that original closed method of winch rope access window easily led to ventilation leakage by use of rubber pad to fix on explosion-proof ventilation door, a reform scheme by use of movable baffle to close the window was proposed. The test results show that exterior ventilation leakage rate is reduced from 15.5% to 6.5% and negative pressure of ventilator is reduced by 318 Pa after reform.