In this study, the secondary evergreen broad-leaved forest with structure and function protected well in the Ecological Botanical Garden of Yuxi City Center was taken as the study site;six nitrogen concentrations of 0, 1, 5, 10, 15 and 30 g / (m 2·a) N were employed as the experimental treatments, respectively;spray under the forest canopy was adopted for two years, and the 0-10 cm topsoil was collected to determine the soil total organic carbon, total nitrogen, labile organic carbon and its turnover rate, microbial biomass carbon and nitrogen. The study results showed that atmospheric nitrogen deposition with the medium and high concentrations apparently increased the content of soil total carbon and nitrogen, decreased the content and turnover rate of labile organic carbon, and reduced the content of microbial biomass carbon and nitrogen, indicating that atmospheric nitrogen deposition with the medium and high concentrations could affect the process of soil carbon cycle and nitrogen cycle, expand the carrying capacity of soil carbon and nitrogen, change soil carbon components, delay the conversion process of soil carbon, and reduce the amount of soil microbial biomass of subtropical evergreen broad-leaved forests. The correlation results of data analyses showed that a polynomial relationship between soil total carbon and atmospheric nitrogen deposition concentrations occurred, i. e., soil total carbon increased with the rise of atmospheric nitrogen deposition concentration, reached the maximum value at the 10 g / (m 2·a) N level [i. e., (31. 05±1. 94) g / kg], and then decreased with the continuing rise of atmospheric nitrogen deposition concentration;a positive linear correlation between soil total nitrogen and atmospheric nitrogen deposition concentration occurred, i. e., soil total nitrogen increased with the rise of atmospheric nitrogen deposition concentration;and soil labile organic carbon and its turnover rate, the content of microbial biomass carbon and nitrogen, respectively, showed a negative linear correlation with atmospheric nitrogen deposition concentration, i. e., they decreased with the rise of atmospheric nitrogen deposition concentration. [ABSTRACT FROM AUTHOR]