human activities exacerbate the production and emission of reactive nitrogen and lead to the increase and globalization of nitrogen deposition. at present, the interference of human activities in the global nitrogen cycle has exceeded the boundaries of the safe operation of the earth system. high nitrogen deposition has threatened the health and safety of the ecosystem and has become a hot issue that needs to be clarified and solved in the process of ecological civilization construction. this review summarizes the impact of nitrogen deposition on forest ecosystems from the aspects of nitrogen deposition on forest plants, animals, and microorganisms by referring to the literature on nitrogen deposition, introduces the corresponding response mechanism, and includes how we analyze and compare the data (methodology) and clarify what the effects of nitrogen deposition on the forest ecosystems, how forest ecosystems respond and acclimate longterm n deposition(results).