【Objective】Soil microbes are the drivers of material circulation and energy flow in ecosystems, and their community structures may be used to characterize responses of soil ecological processes to environmental changes. This study was conducted in a natural Altingia gracilipes forest in the subtropical area and lasted for two consecutive years. This study was oriented to explore impacts of nitrogen (N) deposition on the dynamics of soil microbes, 【Method】 An in-situ N deposition simulation experiment was designed to have three treatments, i.e. CK (0 kg·hm^-2·a^-1), LN (50 kg·hm^-2·a^-1) and HN (100 kg· hm^-2·a^-1) in N deposition level, was carried out in 2010—2011, and the technique of phospholipid fatty acids (PLFAs) was used to explore diversity and composition of the soil microbial community.【Result】Results show that the soil microbial community in the forest consisted mainly of bacteria, gram-positive bacteria, gram-negative bacteria, fungi and actinomycetes. Among them, bacteria were the dominant fraction, contributing 78.3% to the total microbial PLFAs content. Significant differences were found between treatments and seasons in soil microbial community structure. Treatment LN had its soil microbial community structure altered significantly only in summer, when increased abundances were observed of bacterial, Gram-positive, Gram-negative and fungal residual PLFA markers but not i17:0, a17:0, 18:1ω7c, and 18:1ω7t markers. Treatment HN varied with the season, too, in soil microbial community structure. Decreased abundances of 16:1ω7c, 16:1ω7t, 18:1ω7t, and cy17:0 markers were found in spring, and of 18:1ω9 and 18:2ω6,9c markers in winter. In addition, no significant change was found in ratio of fungi to bacteria and of Gram-positive bacteria to Gram-negative bacteria in either Treatment LN or HN, but a significant one was in content of special fatty acids, such as cyclopropane fatty acid or isomeric fatty acid. Treatment LN increased the ratio of cyclopropane fatty acids to Precursor fatty acids all the year around, and also the ratio of isomeric fatty acids to anti-isomeric fatty acids in winter and spring, while Treatment HN increased the ratio of isomeric fatty acids to anti isomeric fatty acids in summer and autumn, but did not affect much the ratio of cyclopropane fatty acids to Precursor fatty acids throughout the entire experimental period. So the effects of N deposition on soil microorganisms do vary with seasons. Therefore, it is necessary to take season into consideration when the impacts of N deposition on soil microbial community structure in the subtropical forest ecosystem are studied. 【Conclusion】All the findings in this experiment demonstrate that short-term N deposition changes the soil microbial community structure, but not the ability of the soil microorganisms responding to environmental changes. Soil microbes respond to short-term N deposition through changing the content of special fatty acids, however, the response varies with the season. Comprehensive analysis shows that the change in soil microbial community structure is not only affected by soil substrate availability, but also soil temperature, moisture and other environmental factors that varies with the season. So they may serve as important factors affecting changes in soil microbial community structure in the subtropical evergreen broad-leaved forest. All the findings in this study may serve as reference for exploration of the mechanism of soil microbes affecting soil nutrient cycling in the subtropical natural forest as affected by nitrogen deposition in future. As the experiment was quite short in time, it is quite possible for soil microorganisms to get adapted to long-term nitrogen deposition. Therefore, in the context of steady increase of nitrogen deposition in the future, a long-term field experiment on nitrogen deposition should be carried out using high-resolution molecular biology methods, for better understanding of the mechanisms of soil microorganisms responding and adapting to nitrogen deposition in subtropical forest ecosystems.