For studying the possibility of detecting water quality by remote sensing, simultaneous field experiments at Taihu Lake (one of the three famous eutrophic lake in China) were made in winter and summer to measure the reflected light spectra on water and to get water samples for chemical analysis. Statistical analysis with experiment data shows that (1) there is good correlation between COD Mn and chlorophyll a concentration;(2)in summer, north Taihu Lake, the reflectivity spectra of light on water is affected mainly by chlorophyll a concentration, which can be expressed by a liner correlation model and it is most obvious at wavelengths larger than 700nm;(3)in winter, the reflectivity spectra of light on water is affected mainly by suspended substance concentration in a wide wavelengh range, which can be expressed by a log liner correlation model or by a liner correlation model more suitably if only the suspended substance concentration less than 100mg/L is considered, and it is more obvious at wavelengths between 500-800nm.The statistical models about lake are made between the surface spectral reflectivity at different wavelengths and the water quality parameters.