[Objective] Freeze-thaw cycle is an important physical process in alpine regions, the objective of this study was to elucidate the impact of freezing and thawing on the microstructure of alpine meadow soils with varying degrees of degradation. [Methods] Alpine meadow soils with different degradation degrees in Menyuan, Qinghai Province, were used as the research objects, and different root contents were used to characterize different degradation degrees. Freeze-thaw cycle test and scanning electron microscopy were carried out on remolded specimens to analyze the effects of different numbers of freeze-thaw cycles, water contents, and root contents on the microstructure of meadow soils under freeze-thaw conditions. [Results] The pore fractal dimension of alpine meadow soils continued to increase with the increase in the number of freeze-thaw cycles, the average diameter of the pores showed a decreasing trend and stabilized after seven freeze-thaw cycles, the increase in porosity was concentrated in the first four freeze-thaw cycles. The higher the mass water content of the meadow soil, the greater the increase in porosity after freezing and thawing. When the mass water content was＞40%, the fractal dimension of the pores of the specimens increased dramatically after freezing and thawing, while the average diameter of the pores decreased significantly. Plant roots significantly inhibited the effect of freezing and thawing on the pore space of alpine meadow soil, and the decrease of the average diameter of the pore space after freezing and thawing decreased from 16.19% to 0.16%, and the increase of the porosity decreased from 33.22% to 18.17% with the increase of root content of the specimen.[Conclusion] The higher the degradation degree of alpine meadows, the greater the impact of freezing and thawing on the microstructure of the soil. The plant root system can significantly affect the stability of the soil structure. The findings of the study offer a foundation for further theoretical inquiries into the dynamics of degradation control and its influencing factors within alpine meadows.