Abstract: To reveal the mechanical response and damage mechanisms of foliated rocks in deep underground excavations, a series of true triaxial tiered cyclic minimum principal stress (σ3) tests were conducted on slate specimens with different foliation orientations combined with acoustic emission (AE) monitoring. The results indicate that most slate specimens fail when the σ3 is unloaded to a critical value, exhibiting cumulative and time-delayed failure characteristics. In contrast, specimens with foliation planes parallel to the σ3 direction show low sensitivity to changes in σ3. Moreover, the deformation characteristics of specimens are primarily controlled by stress anisotropy, with relatively weaker influence from structural anisotropy. The deformation in the maximum principal stress (σ1) direction exhibits an obvious memory effect, varying significantly only when σ3 falls below the previous minimum. The relative residual strain of specimen in the σ1 direction generally follows a trend of decrease-stabilization-increase with cycle number, and, for failed specimens, its final increase stage may indicate accelerated irreversible deformation before failure. Additionally, the cyclic energy density of specimen decreases first and then increases with cycle number, reflecting the initial structural strengthening and later-stage yielding failure processes. The AE activity is concentrated at the minimum stress point of each cycle, and the b-value exhibits a variation trend similar to that of σ3. These findings clarify the damage evolution of foliated slate subjected to tiered cyclic σ3 loading under true triaxial conditions, considering the coupled effects of foliation orientation, stress anisotropy, residual deformation, energy evolution, and AE response.