On the basis of located observation, we chose Fraxinus chinensis plantations as research objects, and bare land as control, on coastal saline-alkali soil as microclimate monitoring site. We studied dynamic, thermal, and hydrological effects of F. chinensis plantations, so as to provide some reference for ecological impact assessment of artificial afforestation on coastal saline-alkali soil. The results showed as follows. The solar radiation, wind speed, soil temperature and soil moisture in the plantations were obviously lower than that on bare land, while the air humidity was higher. Compared with the bare land, the air temperature in plantations was higher in spring, but lower in summer and autumn. The windbreak effect and shade effect reached 77.87% and 67.5%, respectively, in summer. Compared with bare land, the air temperature in plantations decreased by as much as 0.40 ℃, but the air humidity increased by 7.59% -18.61%. There was a very significant correlation between any two of different microclimate factors within the forest, especially the correlation between air temperature and soil temperature.