Trophic state index is an important and synthetic standard for estimating the pollution status of water body. It requires large scale field sampling work and complicated indoor chemical analysis involving traditional analytical techniques, as well as complex calculations applying complicated formulas. In this study, through the analysis of the hyperspectral remote sensing data and the water body trophic state level, the remote sensing reflectance and trophic state index of the water body, Lake Taihu, are calculated, The result of correlative analysis, found the hyperspectral sensitive bands to be inverse to the water-body^, s trophic state index and sensitive bands and bands^, combination (ratio) in established models. The comparative baseline model selected is a power function model TSI_C =68. 76χ^0.5199, with an independent variable of R_717nm. The result, through precision analyses using the other 12 points, found the differences between practice and forecast along half one grading interval, therefore providing reliability and practicability. In conclusion, it is possible to monitor a water-body^,s trophic state index directly with hyperspectral remote sensing data and some evidence for the theoretical basis of investigating water quality in a large scope using hyperspectral remote sensing data is justified.