Abstract: This study presents an approach to the determination of the trophic parameters of chlorophyll-a from field reflectance spectra in Nanhu lake in eutrophic status in Changchun.The reflectance spectra was measured using ASD FieldSpec spectrometer from April to september in 2004.Based on in situ water samplies and the reflectance measurements,the features of the spectral reflectance of the water are discussed.Algorithms are developed to evaluation the spectral data.The single band R_753nm,the spectra ratio of R_753nm /R_681nm,and the reflectance first-derivative of 700 nm,showing a linear relationship,are found to be significantly correlated with the concentration of chlorophyll-a,and the determinative coefficient R² gained by using the single band is higher than that gained with other two models.There is satisfactory correspondence between hyperspectral models and chlorophyll-a concentration,therefore,it is possible to monitor the water quality of Nanhu lake throngh the hyperspetral remote sensing data.