<p>This study investigates the micro-morphological evolution and fracture behavior of granite under freeze-thaw (F–T) cycles, aiming to elucidate the mechanisms governing F–T deterioration. Granite specimens were subjected to laboratory F–T cycling tests. Microstructural alterations were examined using scanning electron microscopy (SEM), while the complexity of morphology was quantitatively assessed via fractal dimension analysis. The extent of weathering was evaluated based on the loss of P-wave velocity. Results demonstrate that F–T cycles induce cumulative damage in granite, manifested mainly through the detachment of unstable mineral particles and the progressive extension and interconnection of pre-existing microcracks. The fractures displayed by F–T cycles exhibit distinct characteristics of brittle fracture. The fractal dimension of fracture surfaces exhibited a fluctuating increase with continued F–T cycles, indicating growing complexity in micromorphology. As the magnification increases, the fractal dimension value increases, and so does the randomness. However, after 60 F–T cycles, the extent of these morphological alterations remained relatively constrained. Based on P-wave velocity reduction criteria, the samples were classified as slightly weathered. These findings contribute to a deeper understanding of the micro-scale degradation mechanisms in granite under F–T conditions. The study offers valuable insights and references for the construction and maintenance of engineering projects in cold regions.</p>