For Liujiazhuang railway tunnel of Shanghai-Kunming through the coal strata in construction of large deformation phenomenon, based on theoretical analysis, numerical simulation and field monitoring method, analyzes the reason of large tunnel deformation, deduce and verify the initial position of large deformation, the constraints of unit cell along the inclined plane direction of coal seam above the stress state and the tunnel into the containing tilted strata horizontal distance between the change rule, the stress and deformation of the element body and the primary support structure of the inclined coal seam are analyzed. The result showed that the stress state of the coal element above the palm face increases with the horizontal distance between the palm face and the bottom of the inclined coal seam, and the rock mass goes through three deformation stages of extrusion, compression shear and shear slip. The large deformation of surrounding rock and the failure of primary support structure both occur in the early stage of shear slip stage, so shotcreting to palm face, grouting reinforcement to coal seam up the palm face and strengthening the stiffness of primary support should be taken to prevent the large deformation of the tunnel in the stage of compression and shear deformation combined with the field monitoring data, which can provide theoretical reference for the same type of tunnel with large deformation.