In order tO solve the problem of rib spalling of high coal walls in fully-mechanized (HCWFM) mines, we used the principle of damage mechanics to analyze coal wall rib spalling. The results show that coal wall rib spalling is, to a certain degree, a macro-performance of the development of micro-cracks. We built a mechanical model to simulate the damage to the front of coal walls, carried out theoretical calculations of the damage parameters, analyzed the effect of mining height, original cracks, seam strength, horizontal stress, vertical displacement of the coal walls and other parameters on coal wall rib spalling,which conform well with the results of our field measurements and numerical simulation. The key to control coal wall rib spalling is to control the development of cracks in coal walls. Accelerating the speed of advancing the working face, improving the setting load of support and the horizontal force of the guard board, strengthening coal walls and other technical measures can effectively reduce the degree of damage to the coal walls and control coal wall rib spalling at HCWFMVl faces.