Abstract: Forest is the direct acceptor of large-area nitrogen deposition, carbon pool of forest soil accounts for 45% of the whole forest ecosystem carbon pool. The increasing nitrogen deposition has a profound impact on the input and output of forest soil carbon pool, and then affects the structure, process and function of forest ecosystem.To investigate the possible mechanism of nitrogen deposition, four processes of nitrogen deposition (litter decomposition, fine root turnover, soil respiration, dissolved organic carbon leaching) affecting forest soil carbon pool input and output were reviewed, the existing problems in the response of forest soil carbon input and output process to nitrogen deposition were discussed, and the emphasis and direction of future research were pointed out.