To study the effects of soil fauna on the rates of litter decomposition and soil nutrients return, litters of Carex cinerascens, Triarrhena lutarioriparia, and Phragmites australis were collected from Lake Poyang Wetland in November 2017. An in situ simulation experiments with three types of litters were carried out by the litter bag method. Decomposing bags with mesh sizes of 4.5 mm (large) and 0.1 mm (small) were used to assess the contribution of soil fauna in this study. The results showed that:the decomposition rate of litters was different among plants, with a significant higher decomposition rate of C. cinerascens than those of T. lutarioriparia and P. australis. There was a negative correlation between litter decomposition rate and litter carbon accumulation/nitrogen accumulation index (NAI_TOC/NAI_TN), and the remaining dry mass of litters; while a positive correlation with litter total phosphorus content; the total nitrogen content was different among litters, which has a degressive sequence as C. cinerascens, T. lutarioriparia, P. australis; the decomposition rate showed the same sequence among litters-the higher nitrogen litter, higher decomposition rate. The participation of soil fauna promoted the decomposition rate and the release of nutrient elements from litters and then regulated the return process of C, N, P elements to soil nutrient bank. This study will provide scientific data for the study on nutrient cycling of wetland ecosystem.