Abstract: In order to study the deterioration mechanism of slope rock mass under the action of freeze-thaw cycles, taking the rock slope of an open-pit mine in Xinjiang as the engineering background, a comprehensive series of test methods such as freeze-thaw cycle tests, direct shear tests, and acoustic emission tests were carried out on feldspar sandstone samples. The influence mechanisms of different numbers of freeze-thaw cycles on the physical properties, shear mechanical properties, and acoustic emission characteristics of feldspar sandstone were elaborated in detail. The research results show that: with the increase of the number of freeze-thaw cycles, the mass and longitudinal wave velocity of feldspar sandstone show a downward trend, and the rate of decrease gradually slows down; as the number of freeze-thaw cycles increases, the failure of feldspar sandstone gradually changes from brittle failure to plastic failure. Under a high number of cycles, feldspar sandstone produces a greater shear displacement during the compaction stage, the curve trend is gentler, and the slope of the elastic stage is lower, indicating a decrease in the deformation resistance ability of the rock; with the increase of the number of freeze-thaw cycles, the cohesion of feldspar sandstone samples shows a trend of first rapidly decreasing and then tending to be stable; as the number of freeze-thaw cycles increases, the internal friction angle of feldspar sandstone samples shows a downward trend with an increasing rate; with the increase of the number of freeze-thaw cycles, the cumulative number of acoustic emission ringing counts in the post-peak stage of feldspar sandstone still increases rapidly, the internal cracks of the sample develop rapidly, and the residual strength further decreases. The reason is that the tensile stress generated by the internal temperature effect of feldspar sandstone under the freeze-thaw action and the frost heaving force generated when the pore water freezes lead to the development of internal pores, increasing the degree of rock damage, reducing the rock’s deformation resistance ability, and destroying the interlocking between tiny particles inside the rock mass. At the same time, with the increase of the number of freeze-thaw cycles, the freezing and consumption of water inside the sample occur, and the internal frost heaving force of the sample gradually decreases, and the loss range of mass and longitudinal wave velocity gradually decreases.