Abstract: In order to solve the problems such as gas outburst in roadway tunneling, frequent overlimit of gas concentration in mining face, and replacement tension in mining face in high gassy coal seam, taking 1902 working face of Gaoshan Coal Mine as the engineering background, the gob-side entry retaining technology of in-situ filling in high gassy outburst coal seam was studied.Theoretical analysis was used to determine the in-situ filling and supporting mode of precast concrete block and get the width of filling wall was in the range from 0.72 m to 1.68 m; by using FLAC^3D numerical software, the surrounding rock plastic zone, stress and displacement distribution law of roadway under different width of isolation wall were analyzed under conditions of 0.8 m, 1.2 m, 1.6 m wide walls, and the field test and mine pressure monitoring were conducted in 1902 working face.The results show that: with the increase of the width of the filling separation wall, the roof cutting ability of the wall increases, the stress and displacement deformation of surrounding rock of roadway decreases, and the reasonable width of the wall is determined to be 1.2 m.The total average displacement of the roof and floor of the retaining entry is basically maintained at 250 mm±50 mm, and the average total displacement of the two sides is maintained at 200 mm±20 mm, which verifies the feasibility of the technology and provides a reference for the application of gob-side entry retaining technology in coal mines under similar conditions.