The change in soil microclimate could affect many ecosystem processes,and study on soil microclimate' s response to warming will be helpful in climate change project. In this study, open-top chamber (OTC) was employed to investigate the response of soil microclimate to warming in a alpine steppe in Northern Tibetan Plateau. The results showed that : there was apparent diurnal and seasonal variation in soil microclimate in the alpine steppe ; OTC elevated annual average air temperature by 3. 2℃,soil temperature by 5. 2℃ ;OTC could significantly elevate soil temperature, more increase in non-growing season than in growing season ; OTC could significantly elevate soil moisture in winter, while reduce the soil moisture in summer. This paper analyzed the response of soil microclimate to warming,and the results are helpful in studying the effect of climate change on hydrothermal regime in alpine region.