Chlorophyll-a concentration is an important indicator for estimating the eutrophication degree of a lake. Taking advantage of the water qualities experimental data on 27 and 28 October, 2003, the paper constructs the chlorophyll-a concentration estimating model for Taihu Lake, China. And then, the study uses this chlorophyll-a concentration estimation model to estimate the seasonal distribution pattern of chlorophyll-a concentration from CBERS-1 imageries on 5 April, 28 April, 16 May, 5 August, and 30 October of 2006, and 5 July, 2007. According to the research results, it was found that the chlorophyll-a concentration is lower in summer and higher in autumn and winter, and could illuminate the four stages of phytoplankton growth in a year; Compared with the previous study reports, the chlorophyll-a concentration is higher than the actual concentration by estimating from the CBERS-1. There are still some problems for applying the CBERS-1 imageries to water qualities remote sensing, which should be improved by further study.