<p>This study investigates the stiffness evolution characteristics of various rock types through damage-controlled pre-peak uniaxial cyclic compression tests, with special emphasis put on the influences of porosity and lithology. The results demonstrate that the bulk modulus increases monotonically during pre-peak loading. In contrast, the shear modulus initially strengthened, then degraded linearly with the increasing equivalent irreversible strain. Subsequently, a dual-linear evolution model is proposed to characterize the evolution of rock moduli. An increase in rock porosity can lead to a significant decrease in rock modulus, especially when the porosity is below 5 %. Correspondingly, the stiffness-strengthening potential of rock reduces significantly with the increasing porosity below this threshold and rises again when rock porosity exceeds 5 %. However, in some available literature, rocks do not gain stiffness strengthening but undergo continuous stiffness degradation under cyclic loads. Such a discrepancy stems from the mesoscopic mechanical behaviors controlled by the mineralogical and structural characteristics of rocks. Generally, two competitive effects, i.e., contact deformation resistance and microfracturing, drive the evolution of rock stiffness. When the contact deformation resistance effect between grain boundaries and fracture surfaces predominates, rocks are prone to experience stiffness strengthening; when the propagation of microfractures surges, rocks are more likely to undergo stiffness degradation. These findings contribute to a better understanding of the evolution of rock stiffness under compressive loads.</p>