Abstract: In order to solve the problem of gas overrun in long wall face at Yangcunpu Coal Mining in Sichuan depression, this paper analyzed the migration path and abundant region of pressure-relieved gas and optimized the drainage parameters by means of strata movement theory and the roof-cross borehole gas drainage field tests. The results showed that the best drainage region is under the overlaying key strata due to its significantly impediments to gas, and that field test results accord with theoretical analysis, and that the reasonable gas drainage parameters were determined and gas drainage efficiency was improved remarkably, and that the unsafe factor of gas overrun was successfully eliminated and the drained gas was used to generate electricity. The successful experiences can be introduced to other similar mines due to good social and economic effect.