Freeze-thaw is an important physical factor affecting soil structure in alpine regions. Taking alpine meadow in Qinghai Lake basin as the research object, the influence of freeze-thaw cycle on the structure characteristics of soil macropores in the frost mounds and the inter space of frost mounds were studied through collecting undisturbed soil columns, simulating freeze-thaw cycle, conducting CT scanning and image interpretation. The results showed that with the increase of the freeze-thaw cycles, the soil macroporosity in the frost mounds and the inter space of frost mounds presented a trend of "decrease-increase-decrease", and the decrease of soil macroporosity by freeze-thaw cycles was mainly formed in the first freeze-thaw cycle. The variation trends of the average equivalent diameter, average volume, average branch length, branch density and node density of macropores were basically the same as that of macroporosity. The effect of freeze-thaw cycle on the soil macropores in the frozen mound was significantly greater than that in the inter space of frost mounds. There were two peaks of the soil macroporosity along the depth in frost mounds, and the size and position of the peak value changed. Soil pore structure was more sensitive at a depth of 30—80 mm in the frost mounds than other depths of the felt layer.