The Changbai Mountain tundra is the only typical alpine tundra of eastern China and eastern Eurasia. In the recent 30 years, herbaceous plants have invaded from low altitude to the alpine tundra, which transformed shrub tundra to shrub-herb-mixed tundra and herb tundra, causing significant changes to the litter components. To understand the response of chemical composition and ecological stoichiometric characteristics of three types of litter to simulated nitrogen deposition in the Changbai Mountain tundra, an artificial simulated litter decomposition experiment was designed and conducted. Rhododendron aureum (native dominant shrub species) litter, Deyeuxia angustifolia (invasion herb species) litter and Rhododendron aureum-Deyeuxia angustifolia-mixed litter collected from the Changbai alpine tundra were used to set up nitrogen addition experiment at three levels under laboratory condition:control group (CK:without nitrogen addition), low N level group (LN:10 g N m^-2 a^-1)), and high N level group (HN:20 g N m^-2 a^-1)). Then we collected litter after decomposition and measured the content of C, N, P and lignin (Li), aiming to study the differences of chemical composition and ecological stoichiometric characteristics of the litter with different components and nitrogen addition levels. The results showed that:(1) Without nitrogen addition, the content of C and P in the litter reduced significantly while the content of Li increased at the beginning and then reduced; the content of N in the R. aureum litter increased significantly while the content of N in the R. aureum litter and the mixed litter reduced. C/N, C/P, Li/N of the litter of three types decreased by R. aureum>R. aureum-D. angustifolia-mixed>D. angustifolia; N/P of the litter of three types decreased by D. angustifolia>R. aureum> R. aureum-D. angustifolia-mixed. (2) The simulated nitrogen deposition promoted the release of nutrients during decomposition process and the promoting effects of high nitrogen addition turned out to be more significant. C/N, C/P, N/P, Li/N of the R. aureum litter decreased rapidly at a certain nitrogen addition threshold then the effects on ecological stoichiometric characteristics would be weakened if more nitrogen was added. In our study, high nitrogen addition promoted the decline of C/N and Li/N of the D. angustifolia litter. (3) Change of litter components caused by herbaceous species invasion would promote the decomposition of litter and affect the nutrient cycle mechanisms of Changbai Mountain alpine tundra. As nitrogen deposition increased, the contents of C, N, P, Li and C/N, Li/N of the D. angustifolia litter decreased further and refractory compounds decreased. Nitrogen deposition accelerated nutrients cycle between the D. angustifolia litter, soils and herbaceous plants. Thus, we suggest that the increase of nitrogen deposition will be more favorable to the win of D. angustifolia in the competition with R. aureum, which will impulse meadowization trend in the Changbai Mountain alpine tundra.