Human activities in the past decades have increased the nitrogen input in terrestrial ecosystem, which has created 3 kinds of effect on litter decomposition, including promoting effect, restraining effect and no effect. Litter decomposition is affected by the substrate quality of the litter, including lignin, cellulose, phenolics, N concentration, P concentration, C/N ratio, C/P ratio and lignin/N ratio. The global changes (such as elevated CO_2, global warming, changes in precipitation) resulted from anthropogenic activities have affected the rate of N deposition and litter decomposition. The future research hotspots in the regard include the effect of N deposition on litter decomposition in the tropical forests and subtropical forests and on the decomposition of litter of broad-leaf species, a long-term effect of nitrogen deposition on litter decomposition, using~(13)C isotope to study litter decomposition, and the interactions between N deposition and elevated atmospheric CO_2, global warming, changes in precipitation, elevated ultraviolet, phosphorus sedimentation.