Southeast Tibet seasonal permafrost distribution is very wide, freeze-thaw cycle action on seasonal permafrost area moraine soil shear properties have significant impact. In order to investigate the freezing and thawing cycle action and water content on the mechanical properties of moraine soil, to southeast Tibet Linzhi area yigong landslide disaster point moraine soil as a research object, to carry out the number of freezing and thawing cycle and water content under the condition of different conditions of large-scale straight shear test. Test results show that: moraine soil shear curve is roughly divided into elastic deformation, strain hardening, plastic yield three stages; The tumbling and misalignment of soil particles during shearing resulted in a sudden increase or decrease of stress between soil particles in a short period of time, and fluctuations in the shear stress-displacement curve of the specimen;The cohesion of moraine soils after undergoing freeze-thaw cycles decreases in a negative exponential function, while the angle of internal friction fluctuates in the range of 38.65° to 42.9°; The more the number of freezing and thawing of moraine soil, the smaller the shear expansion of moraine soil, the larger the shear shrinkage, and the maximum shear shrinkage of the specimen with freezing and thawing cycle T = 20.