Abstract: The granite residual soil is a typical soil widely distributed in the coastal areas of South China and other rainy regions. Due to its unique geological formation, it exhibits both high strength and large porosity, making it widely used in underground engineering. The dynamic mechanical properties of granite residual soil in different sample states (undisturbed, remolded, and saturated) are investigated through the dynamic triaxial tests. The results indicate that the dynamic response of the granite residual soil is significantly influenced by its structural characteristics and external loading conditions. Under low cyclic loading and small dynamic stress amplitudes, the undisturbed samples demonstrate strong resistance to deformation due to their natural structure. However, at higher dynamic stress amplitudes and cyclic loading, their structural integrity is gradually destroyed, leading to significantly increased dynamic strain, even exceeding that of the remolded samples. The dynamic strain of 0.25% is identified as the critical threshold for stiffness degradation in the granite residual soil, and below this value, the samples exhibit high stiffness, while the stiffness decreases markedly beyond this threshold. The relationship between dynamic shear modulus and dynamic strain exhibits nonlinear behavior. The hysteresis loops and dynamic backbone curves are well-fitted using the Hardin-Drnevich (H-D) constitutive model, though the model shows some limitations for the intact samples under low dynamic stress. These findings provide valuable insights for predicting and optimizing the performance of the granite residual soil under complex engineering conditions.