Abstract: In order to efficiently extract gas in advance before the deep coal seam mining and ensure the safe mining of the deep coal seam, the L-shaped horizontal well drilling technology is one of the main methods of surface gas drainage. There are many difficulties in drilling horizontal well for L-shaped gas drainage through goaf, which is one of the important research topics of coal and gas co-mining in coal mining area. Mainly from the three aspects of well structure design, nitrogen drilling technology through goaf, and drilling trajectory control technology in horizontal section, the key technology research of L-shaped gas drainage horizontal well drilling through goaf is carried out in detail. The research results of key technologies were successfully applied to an L-shaped surface gas extraction well through goaf in M mining area, and the well was efficiently and smoothly drilled, making the penetration rate of horizontal section of target deep coal seam about 90%.