Abstract: At present, we still lack a deep understanding of the response direction and amplitude of root exudate flux and related ecological consequences to different nitrogen（N） deposition levels. In order to reveal the difference in the effects of different N addition treatments on root exudate C flux and its mediated soil nutrient transformation process, the typical Betula albosinensis Burk forest in the mountainous area of southwest China was used as materials, and different nitrogen deposition levels were simulated by in-situ N addition experiment(control group, 0 kg·hm^-2·a（-1）); low nitrogen treatment, 25 kg·hm^-2·a（-1）; High nitrogen treatment, 50 kg·hm^-2·a（-1） respectively. The results showed that:（1）N addition significantly reduced the C input rate（the average root exudation rate per unit root biomass decreased by 14.87% under low nitrogen（N25））and annual C input flux of root exudates（about 45.01% reduction under low nitrogen condition）（P＜0.05）, and high N treatment had stronger inhibition effect on root exudates C input.（2）N addition significantly inhibited soil N mineralization rate and related microbial extracellular enzyme activities（P＜0.05）, and significantly reduced its rhizosphere effect. In conclusion, N deposition significantly inhibited the root exudates C flux and its mediated soil nutrient transformation process, and this inhibition effect increased with the increase of N deposition level.The results could enrich the understanding of carbon-nutrient cycling in forest under global climate change.