Abstract: In view of the large gas emission and gas accumulation in the upper corner of the fully mechanized top coal caving face in Wangzhuang Coal Mine，a directional drilling technology with large di⁃ ameter is proposed to control the gas overrun in the goaf and upper corner. By studying the evolution pro⁃ cess of goaf fractures along with the advance of the working face，the development height of roof fractures is analyzed，and the optimal hole layout layer and drilling structure of large diameter high-level directional long boreholes are determined，and the engineering practice is carried out. The results show that the gas concentration in the boreholes is relatively high at the beginning through the arrangement of large-diameter high-level directional long boreholes in the high gas working face，but with the continuous progress of the working face，the gas concentration in the boreholes began to decline，and the large-diameter high-level directional long boreholes continued to extract gas from the upper corner for a long time，and the net amount of gas extracted was stable. The average net amount during the drilling drainage was 4.3 m³/min， and the average concentration of the boreholes was 11.1%，It effectively solved the problem of gas overrun at the upper corner and ensured the safe mining of the working face.

Key words: upper corner, directional drilling, high drilling, mining fissures