High temperature and gentle breeze were one of the key factors for the algae bloom formation in Lake Taihu.The days when temperature was higher than 25℃ at 14:00 and wind speed was less than 4 m/s at the same time were selected, and EOF anaiysis, cluster analysis of eight directions and divergence spatial distribution were used for studying the wind field from 17 meteorological stations in 2001-2007 around Lake Taihu.The spatial characteristics of selected wind field showed that the southeast wind was the major pattern.When any direction wind passed across the lake, the significant divergence appeared above the downwind lake surface and near its banks.The divergence field center was observably in the southwest area of Lake Taihu.Furthermore, statistical analysis on the observational data from 4 meteorological stations, such as Wuxi, Yixing, Dongshan and Wuxian, with days meeting the above-mentioned weather conditions, was put forward during 1961-2007.The numbers of days with high temperature and gentle breeze per year were less and the beginning time of such weather conditions was later before 1982.Oppositely, the numbers of such days per year was more and the beginning time was earlier after 2004.Both of them showed oscillation during 1982 to 2004.