In order to simulate changes in natural nitrogen deposition and explore the effects of nitrogen addition on soil organic carbon and soil respiration, four treatments (CK (control), N50 (50 kg/(hm²·a) of N), N100 (100 kg/(hm²·a) of N) and N150 (150 kg/(hm²·a) of N)) were conducted in a subtropical evergreen broad-leaved forest in Wuyi mountain, Fujian Province. The results showed that the effect of nitrogen addition on the TOC of the surface soil (0–20 cm) was not significant, and the effect on the content of its different components is different. Compared to the CK, N100 and N150 significantly increased the soil POC content by 110.7% and 147.9% (p₁ = 0.024, p₂ <0.001). The content of soil MAOC tended to decrease with the increase of nitrogen addition, but the difference was not significant. The annual dynamic of soil respiration rate was unimodal distribution, and nitrogen treatments had different effects on soil respiration in different observation time. Based on fitting equations of soil respiration rate and soil temperature, the annual average carbon efflux of soil respiration in CK, N50, N100, and N150 plots from 2018 to 2020 were 1205.31, 1191.56, 1287.56 and 1128.61 g C/m², respectively. Compared to the CK, annual average carbon efflux of soil respiration did not change significantly in N50, significantly increased by 6.82% in N100 (p<0.001), and significantly reduced by 6.8% in N150 (p<0.001), which meaned that N100 promoted annual carbon efflux from soil respiration, while N150 had an inhibitory effect on it.