Carbon sink produced during rock weathering is an important part of global carbon cycle. Therefore, more and more attention has been paid to this field by the scientists who focus on the global warming. Taking precipitation, evaporation rock, silicate rock and carbonate rock as four end-member components, the authors calculated their contribution rates to the total dissolved mass (TDS) of Poyang Lake water system, which are 10.4%, 21.9%, 30.0% and 37.8%, respectively. The chemical weathering rates of the basin of Xiushui River, Ganjiang River, Fuhe River, Xinjiang River and Raohe River are 27.22, 50.50, 70.30, 64.62 and 63.94 t·km2·a-1, respectively, while the erosion rates in these areas are 11.34, 21.04, 29.29, 26.92 and 26.64 mm · ka-1.