Abstract: Plant communities are an important factor to improve microclimate and driving forces of microclimate change. The importance of plant communities in influencing processes, such as microclimate change and formation has become an essential component of current researches. In this study, a sample site of four different plant community types and an open space in the Genghis Khan Plaza of Hohhot, a semi-arid city, are used as test sites. The research measures wind speed, temperature and humidity data, and performes ENVI-met software simulation analysis to evaluate the impact of the test sites on the microclimate. The results indicate that the plant community shows obvious seasonality differences in their adaptive capacity for microclimate, and the microclimate has a significant correlation with the tree diameter, height, canopy density, and leaf area index. The height, shape and DBH of trees can directly affect the microclimate environment. The 25 meters tall, heart-shaped, medium DBH deciduous trees have the most obvious cooling and damp ventilation effect in summer. The 5 meters tall, cylindrical, small DBH deciduous trees are effective for increasing temperature and humidity and reducing wind speed in spring, autumn and winter. The study reveals the relationship between the quantitative attribute of phytocoenosis and microclimate variables, and determines how key microclimatic variables change with respect to plant community. This study provides a reference and basis for the construction of green space and the planting design of squares in semi-arid areas.