By the use of the meteorological satellite FY-1C/CAVHRR data .estimated are the concentrations of chlorophyll-a in Chaohu Lake. A remote sensing estimating model is proposed by analyzing the correlation of the FY-1C/CAVHRR channel data for watercolor monitoring and synchronal field survey for chlorophyll-a concentrations. The result indicates that meteorological satellite FY-1C can be used to monitor concentrations of chlorophyll-a in large lakes as a kind of important assistant means of routine water quality sampling survey with its advantages of time and spatial resolution.