Abstract: The variation of atmospheric sulfur sources in Poyang Lake Eco-economic Region was explored by sulfur isotopes in epilithic mosses which collected from the research area during 2012 to 2013, and then compared it with the existing research δ³⁴S values of rain and coal. The results showed that all of the δ³⁴S values of epilithic mosses performed as positive value at a range of 1.9‰ to 9.6‰, the average was 4.9‰. It was found a significant negative correlation existed between the δ³⁴S values of epilithic mosses (x) and atmospheric SO₂ concentration (y) (y=-82.61x+7.63, R²=0.85). The δ³⁴S values of epilithic mosses in Nanchang and Fuzhou were close to the δ³⁴S values of its corresponding city’s atmospheric precipitation. The δ³⁴S values of soil total sulfur were higher than that of epilithic mosses, while the latter was closer to the δ³⁴S values of soil soluble sulfur, showing that the soil enriched more heavy sulfur sources and soluble sulfur in the rhizosphere soil may be mainly derived from atmospheric sulfur deposition. The results indicated that the atmospheric sulfur source in Poyang Lake Eco-economic Region were mainly affected by coal burning and other human activities as well as biogenic sulfur, besides, long-distance transmission sulfur from northerly air masses may be another sulfur source of atmospheric sulfur deposition in this area.