Abstract: In order to solve the gas hazard problem of upper corner by gob-side entry retaining technology in gassy mines, taking the engineering geological conditions of N8205 working face in Tangshangou Coal Mine, Datong, Shanxi Province as the background, based on the methods of field investigation, laboratory test, theoretical analysis, numerical simulation and field observation of rock pressure, the reasonable width of filling wall in gob-side entry was studied. The results show that:the strength of standard specimens made by paste filling material increases rapidly at curing time of 7 days, and the uniaxial compressive strength accounts for 74.8% of the final strength; after the refined modification of the three-dimensional numerical model, the error between the simulated results of the goaf lateral abutment stress and the approach of the surrounding rock of the track drift and the field measured results is small.Under the condition of different filling wall width, the evolution law of axial force, deformation and plastic zone of rockbolt and anchor cable in surrounding rock of gob-side entry indicates that, when the filling wall has reasonable stress environment and the remaining cross-section of the gob-side entry can meet the requirement of gas drainage and return airflow in in-situ test, the optimal width of the filling wall is 2.5 m.