Abstract:In Gaofeng mining section, the comprehensive measures was adopted to treat the mined-out area existed in the No.100 Orebody, including building armoured concrete or concrete isolation layers with high strength, filling the mied-out area with cemented sand or waste boulder, sealing the mied-out area, a surface observation station and an underground monitoring system had been built to observe the displacement of strata or monitor ground pressure, resulting in remarkable success.