<p>The characteristics of surface functional groups, lattice structure, and nuclear chemical shift of coal gangue under mechanical force were analyzed. The mechanical activation mechanism of coal gangue was explored from the molecular structure level. The results indicated that the main components of coal gangue were Si–O and Al-O. The Si–O was relatively stable, and mechanical force could destroy the [SiO₄]⁴⁻ tetrahedral structure to a certain extent, increasing the amorphous Si–O structure. The existing forms of Al-O mainly included four- and six-coordinate polyhedral structures, and the former’s stability was significantly more robust than that of the latter. In the ultrafine grinding process, the Al–OH group on the inner surface of the coal gangue and the hydroxyl group inside the Al-O octahedron was destroyed, and the Al-O six-coordinate structure gradually disappeared. It was considered that Al³⁺ ions in coal gangue enter the three-dimensional structure based on [SiO₄]⁴⁻ tetrahedron to form a more stable [AlO₄]⁵⁻ tetrahedron and other Al³⁺ ions outside the network existed in the form of [AlO₆]⁹⁻ octahedron, which was more easily activated. With the activation effect of mechanical force in the grinding process, the extraction rate of aluminum increased from 7.24 to 62.33%, which also confirmed the above analysis conclusions.</p>