To explore traits related to litter decomposition and the nutrient change of annual herbaceous species under the condition of sediment deposition in the Three Gorges Reservoir. The effects of different sediment depths on ground litter decomposition and nutrient dynamic characteristics of four annual dominant herbaceous species (Digitaria sanguinalis, Echinochloa crusgali, Bidens tripartita, and Xanthium sibiricum) in the water-level fluctuation zone of the Three Gorges Reservoir were investigated using the litter-bag method. Three sediment depths included no burial (0 cm), moderate burial (5 cm) and deep burial (10 cm), were treated with an experimental period of 180 days. The results showed that:(1) During the experiment period, the decomposition rate of litters of four annual herbaceous species was fast at first and then slow. Compared with 0 cm sediment depth treatment, the decomposition rate significantly decreased in 5 cm and 10 cm. (2) When the decomposition ended, the carbon (C) content of four annual herbaceous species litters remained stable, the phosphorus (P) element was released, while the nitrogen (N) was enriched under sediment burial. (3) Except for changes in phosphorus content of D. sanguinalis and E. crusgali litter, the content of carbon, nitrogen and phosphorus of four annual herb litter in 0 cm was significantly lower than that in 5 cm and 10 cm treatment groups. On the contrary, the potassium (K) content of four annual herbs species litters in 0 cm was significantly higher than that in 5 cm and 10 cm treatment group. The results revealed that a large amount of sediment deposition in the water-level fluctuation zone inhibited the decomposition and C, N, and P release of the litter, which is beneficial to reduce the contribution of litter decomposition to water eutrophication and nutrient suspension in the Three Gorges Reservoir, and to a certain extent, has a positive effect on water quality protection.