The effect of the mining height of the 30212 working face of Xiaochang Mine on the coal wall flank of the fully mechanized mining face was studied from both theoretical and simulation aspects, and it was simulated using the numerical calculation software FLAC3D. The results showed that when the mining height was 5.0-7.0 m, as the mining height continued to increase, the amount of roof subsidence gradually increased, and there was an obvious linear increase relationship between them, which reached a peak when the mining height was 7 m. As the mining height increases, the maximum horizontal displacement of the coal wall also gradually increased. After the mining height reached 6.5 m, the maximum horizontal displacement of the coal wall reached 1.05 m. The stability of the coal wall was greatly affected and maintenance was more difficult. The results of the study provided guidance for the rib-spalling control of the mine.