Processed and analyzed the hyperspectral data-Hyperion on August 19^th 2004, we estimated chloro-phyll-a concentration using ratio and differential coefficient method in Lake Taihu. But these two models ^, applicability confined in single area and single phase. In this paper we used mixing spectral analysis model for extracting chlorophyll-a concentration and mapping the distribution of chlorophyll-a concentration. The result shows that the new style of remote sensing data Hyperion can be used for monitoring chlorophyll-a concentration，and that mixing spectral analysis is an optimal method for estimating water chlorophyll-a concentration.