Abstract: In order to improve the gas extraction efficiency of ground drilling,the paper firstly analyzed the failure cases and factors of gas drainage in part ground drilling of Huainan coal mining area,and then took pressure relief gas drainage test at Dingji mine 1422(1) protective seam working face as the background,the destruction laws,that the changes and distribution laws of stress and displacement affected to ground drilling,were researched by using numerical simulation,which obtained the failure causes of ground drilling,and put forward the principles of optimizing and improving drilling.Finally,the optimized drillings were applied to field tests and better gas drainage effect was achieved.