Abstract: Aiming at the severe problem of the large-scale mining face during the recovery period of Xiao bao-dang Mine, using the theory of compression bar stability mechanics and MatLab data analysis software, the structure model of "pressure bar" was established, and the mechanical expression of deflection of coal wall with large mining height was obtained. The formula reveals the distribution law and characteristics of the deflection of the large mining height wall when the guard plate provides different horizontal loads and the length of the guard. It shows that increasing the horizontal load of the guard plate and the length of the guard can effectively control the coal wall gang, and finally demonstrate The stability of the coal wall under different mining heights (5.5m, 6.5m and 7.5m) of Xiao bao-dang Mine provides theoretical support for Xiao bao-dang Mine and similar conditions.