Abstract: Understanding the evolution of meso-structure and mechanical properties of fractured granite under wetting-dr ying and freezing-thawing cycles is of considerable significance for slope stability assessment,safe operation of mining engineer ing,and analysis of long-term service performance.To quantitatively investigate the influence of these cyclic actions on the me so-structure of fractured granite,CT scanning and Low-field Nuclear Magnetic Resonance (LF-NMR) techniques were em ployed to systematically characterise the fracture evolution,pore structure parameters,and pore size distribution of granite spec imens subjected to various cycle numbers.In addition,cyclic loading-unloading tests were conducted to examine the macroscop ic mechanical response.The results indicate that with increasing numbers of wetting-drying and freezing-thawing cycles,both the number and size of micro-cracks within the granite continuously increase,and the fractures gradually evolve from a discrete distribution into an interconnected network,accompanied by a marked enhancement in pore connectivity.The pore structure progressively shifts from being dominated by micropores towards mesopores and macropores;specifically,the proportion of mi cropores decreases by 12.36%,while the proportions of mesopores and macropores increase by 5.54% and 6.82%,respectively.The macroscopic mechanical test results show that the stress-strain response of granite under cyclic action exhibits distinct staged characteristics.After 30 cycles,the peak strength decreases by 8.6% relative to the initial peak strength,displaying a consistently deteriorating trend that is closely correlated with the evolution of pore structure.The wetting-drying and freezing thawing cycles,through repeated water absorption,freezing and thawing,induce pore expansion and fracture coalescence,which constitute the primary intrinsic mechanism responsible for the degradation of mechanical performance in fractured granite.