In order to solve the problem that the roof coal seam of the roadway driving along the floor of No.3 Coal Seam in Bofang Coal Mine was easy to fall and the surrounding rock of the roadway was prone to large deformation, the working face of the mine was changed to driving along the roof of the coal seam, and the deformation and failure of the two sides and the floor of the roadway were serious under the influence of mining. By using the stability control technology of soft thick coal seam, two crossheadings were driven along the floor of coal seam, which could improve the recovery rate of coal seam and increase economic benefits. Through theoretical calculation, numerical simulation and field monitoring, the influencing factors of large deformation of roadway surrounding rock were determined, and the support design was optimized. The soft thick coal seam working face was arranged along the bottom plate to alleviate the problem of large deformation of thick coal seam mining roadway. The scheme provided a reference for solving the roadway support problem of soft thick coal seam in Bofang Mine.