Abstract: Objective To investigate the impact of the "Water Diversion from the Yangtze River to Taihu Lake" project on the estrogenicity of water from Taihu Lake, which is an important source of water in Jiangsu province.Methods Water samples were collected from 8 points of the "Water Diversion from the Yangtze River to Taihu Lake" project from December 2013 to March 2014. Organic constituents in water samples were extracted by solid phase extraction (SPE), the estrogenicity was evaluated by recombinant yeast estrogen screen (YES), and estrogenic phenols were determined by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).Results All water samples could induce significant estrogenic activity; the estrogenic activity of water samples collected from the mouth of Wangyu River was the strongest, and the level of estrogenic phenols was the highest. The nearer of the distance to the mouth of Wangyu River the stronger of the estrogenic activity presented.Conclusions The source water of XD and NQ derived from Taihu Lake were affected by the water diverted from Wangyu River, the intensity of estrogenic activity in Taihu Lake water was positively correlated with the volume of water introduced from Wangyu River.