In Jingchuan's No.2 Mining District,after the 14 line concentrate ventilation shaft collapsed suddenly,serious reverse airflow occurred between the 1150~1000 m main ramp,and fresh airflow could not flow into 1000m haulage level.Therefore,the measure of air flow ejected from air curtain by paralleled fans has been introduced,the velocity of fresh airflow through the main ramp is up to 45 m3/s,the reversal of ventilation airflow between the 1150~1000 m main ramp is avoided availably,and the problem that fresh airflow can not come into 1000 m haulage level also is solved.