Abstract: To investigate the damage evolution of rock masses in cold regions under different disturbance conditions, red sandstone samples are subjected to freeze-thaw cycles and dynamic disturbance tests. Computed tomography images are processed using techniques such as the black top-hat algorithm and three-dimensional visualization to reconstruct models for quantitative analysis of pore and crack development characteristics. This analysis reveals the cross-scale driving mechanisms of rock mass damage under freeze-thaw and dynamic disturbances. Experimental results indicate that in the early stages of freeze-thaw cycling, dynamic disturbance is the dominant factor driving crack propagation. As disturbance intensity increases, the porosity, fractal dimension, and pore connectivity of the sandstone initially increase, reach peaks at 19.81%, 2.64, and 95.56%, respectively, before subsequently decreasing. In the later stages of freeze-thaw cycling, cumulative freeze-thaw damage intensifies the effects of dynamic disturbance, leading to continued increases in porosity and pore connectivity. The sandstone reaches a critical microstructural evolution threshold at a disturbance intensity of 0.05 MPa. Below this threshold, dynamic disturbance promotes the development of microcracks in a "shallow and broad" transverse pattern. Beyond it, crack propagation shifts to a "deep and narrow" longitudinal dominant mode. In addition, freeze-thaw action modulates the degree of freedom for crack extension. The cumulative damage weakens the spatial structural constraints within the rock mass, facilitating the formation of multidirectional, interconnected crack networks and pore systems. These findings provide a theoretical basis for engineering construction in cold regions and for the prevention and control of dynamic disturbance-related disasters.