Abstract: Based on the engineering background requirements of gas extraction and gangue treatment in a mine in Yunnan, a complete set of in-situ filling mining technology for protective layer suitable for gas pressure relief in close-distance coal seam group was proposed. The main principle and design process were expounded, and the key parameters of in-situ filling mining method for protective layer were analyzed. The floor failure depth and equivalent mining height were theoretically calculated, and the filling height of protective layer was designed. The rock failure effect, stope pressure relief effect and protective layer expansion and permeability enhancement effect under the parameters of this group were verified and analyzed by numerical simulation. The results show that the simulation results under the condition of this group of parameters meet the requirements of the regulations. This technical method realizes the efficient and safe mining of coal resources in close-distance coal seams, so as to promote the development of in-situ filling technology of protective layer and provide engineering and technical reference for other mines.