In order to study the deformation and failure mechanism of fractured rock mass under freeze-thaw and periodic load, the macro-meso failure mechanism of fractured sandstone under different freeze-thaw cycles was studied by combining macros-periodic load test with microscopic nuclear magnetic resonance test and numerical simulation of particle flow. The results show that the strength of fractured sandstone decreases with the increase of freeze-thaw cycles, and the expansion phenomenon increases when failure occurs, and the pore size and number increase at the meso scale. The coupling effect of freeze-thaw and degree is more serious. The microscopic performance is that the total area change rate of T2 peak is more obvious and the proportion of large-scale pores increases. The deformation curve trend of fractured periodic load makes the failure cracks of rock samples develop more and more complex, and the damage sandstone under cyclic loading can be used as the basis for judging the threshold range of fatigue strength and obtaining the deformation warning value. The particle flow simulation results show that under the action of periodic load, cracks are concentrated at the tip of prefabricated cracks and the wing cracks are the main propagation mode. Under the action of confining pressure, the failure mode of rock samples tends to be shear-tension composite failure. The research results can provide reference for the stability evaluation and disaster prevention of fractured rock slope in cold region.