1.Yunnan Energy Investment Group Co.,Ltd.，Kunming ,China；2.China Coal Technology Engineering Group Chongqing Research Institute，Chongqing ,China；3.State Coal Mine Safety Technology Engineering Research Center，Chongqing ,China

The gas extraction of C5 coal seam of No.1 Guanyinshan Coal Mine in Yunnan Province is difficult to implement because the mine has complicated geological conditions, high gas pressure, high gas content, soft coal seam,and low coal permeability.To solve the problem, this paper proposed a technology named “drilling and enlarging integration” which increases coal permeability by drilling holes from floor. The technology was implemented in Guanyinshan Mine as a case study. The results show that the exposed area of the drilling holes is increased and the distribution of coal fracture and stress is changed when using the drilling and enlarging integration.After reaming, the average gas concentration of single hole increased by 1.4 times and the drainage volume increased by 2.8 times, and the extraction time is shortened. The paper provides important reference for increasing coal permeability for mines similar to Guanyinshan Coal Mine.