This study aims to investigate the difference of releasing C, N and P between wetland plant litter and overwintering migratory birds' droppings during their decomposition progresses and to investigate the influences of overwintering migratory birds' droppings on the decomposition of wetland plant litter. The decomposition bag technique and birds' droppings addition experiment were conducted from January to June, 2017 on the typical beaches of Lake Paying wetlands. Results showed significant differences of the dry matter loss rates, decomposition rates of three samples (plant litter mixture, wetland plant litter and birds' droppings) in different decomposition times. The mixture is highest, following by plant litter and birds' droppings. The addition of birds' droppings accelerated the decomposition process of plant litter and increased the average decomposition rate by 21.23%. The simulation results of Olson negative exponential model estimated that it would cost 259, 314 and 355 days for decomposing 50% of sample amount of plant litter mixture, wetland plant litter, droppings and about 3.1, 3.7 and 4.2 years for 95%, respectively. The C, N and P of all the three samples showed net release pattern, with significant difference in relative return index. The carbon relative return index (CRRI) of plant litter mixture is highest, followed by the CRRI of wetland plant litter and birds' droppings. While the ranks of NRRI and PRRI (nitrogen and phosphorus) are both birds' droppings, plant litter mixture, and wetland plant litter. The differences of the stoichiometric ratio characteristics of the three samples were also significant. This study speculates that the addition of birds' droppings to the decomposition environment brings additional nutrients, which increases the number, type, activity of the decomposing microorganisms and the stimulation of birds' droppings to produce a series of degrading enzymes such as ligninase, cellulase, sucrase, etc., believed as the key factor for the acceleration of the decomposition process of plant litter. The initial nutrient contents and the changes of stoichiometric ratio of C, N and P during the decomposition process are the dominant factors for the significant difference of decay rate and nutrient release.