Abstract: Aiming at the problem of gas extraction and spontaneous combustion of residual coal in goaf of fully mechanized caving face in spontaneous combustion coal seam, taking 150315 fully mechanized caving face of a mine in Shanxi as an example, the distribution characteristics of cracks and porosity in goaf of this working face are analyzed by theoretical calculation and numerical analysis, and the reasonable horizon of high drainage roadway is given from the perspective of gas extraction. Based on Comsol simulation, the distribution characteristics of gas concentration and spontaneous combustion ' three zones ' in goaf under the disturbance of high drainage roadway at different positions are compared and analyzed, as well as the quantitative variation characteristics of gas concentration and oxygen concentration under different negative pressure of extraction. It is pointed out that the horizontal distance is positively correlated with its disturbance effect on ' three zones ', and its vertical height is proportional to the concentration of extracted gas and inversely proportional to the concentration of extracted oxygen. It is determined that the horizontal position of high drainage roadway is 20 m away from the return airway, the vertical height is 50 m, and the reasonable negative pressure is 20 kPa, which is verified by field practice. After optimization, the extraction amount of high drainage roadway and the gas concentration in the upper corner of the working face are within the safe range. At the same time, the width of spontaneous combustion oxidation zone in goaf is reduced, the risk of spontaneous combustion is effectively reduced, and the cooperative co-governance of gas and coal spontaneous combustion in goaf is realized.