The small scale climate change and water environment in the eastern half of Chaohu Lake was investigated by canonical correspondence analysis(CCA)in 1987-2007.The results were showed as the follows.Annual precipitation,mean temperature per year,and yearly sunlight hours varied constantly in about twenty years with mean value of 1176.19mm,15.96,1906h,respectively.However,annual days of high temperature over 35 showed a significant difference among surveyed years,which ranged within 4~32d/a.Water circum stance of eastern half of Chaohu Lake displayed anonconsistent change with that of climate.In these years,Total nitrogen(T N)and total phosphor(T P)exhibited a convext rack of parabola curve.The rest parameters like CODMn and Chla changed with the concave curve.It was deduced that eastern half of Chaohu Lake was evolving inmeso-trophic status by typical indicators such as eutrophication index(EI,mean 41.22 annually)and nutrient quality index(NQI,1.95~5.86).Relationship analysis indicated that climate factors were closely related with water indicators.Especially,T N,T P,CODMn,and sunlight hours contributed largely to mesoeutropho cation in eastern half of Chaohu Lake,whose influential coefficient was 69%,45%,36%,and 27%.In conclusion,the dynamic of sunlight hours for years will drive predominantly the variation of water quality of eastern half of Chaohu Lake.Especially,when coupling with high contents of T N and T P,the effects of climate factors will be more significant.