Aim: In order to understand the alpine soil ecology process,to provide technical support for the change of biological population and distribution under the global climate change. Methods: The effects of different freezing - thawing treatments(- 2 ℃,- 2 ~ 2 ℃,- 20 ~ 2 ℃) on the number of soil microorganism and activity were studied by simulated freeze - thaw in lab. Results: The results showed that the continuous frozen state reduced the number of bacteria,the number of total microbe,and microbial biomass carbon and nitrogen contents. The severe freeze-thaw decreased the activity of invertase, while moderate freeze-thaw increased the number of bacteria, the total number of microorganisms and the activity of cellulose and catalase. Conclusion: The results suggest that the appropriate freeze-thaw can improve the number of soil microbial and community structure,and thus have a substantial impact on the transformation of soil nutrients and the construction of plant communities.