According to Basic Analytical Methods of Environmental Quality Standards for surface water, GB3838-2002,we used the 1983-2004 monitoring data to evaluate and characterize water quality condition and to analyzewater quality temporal-spatial evolution trend of Lake Dongting, based on the application of comprehensive indexmethods such as Nemerow Index. The results showed that Water quality changed in Lake Dongting which fluctuatedbetween up and down temporally. In 1983-1985,water quality was clean in Lake Dongting. From then on, waterquality had been polluted seriously in 1988 and graduated in light pollution after 199 f,and then ran down in 1999and dropped to light pollution in 2001 again, as well as had begun to aggravate in 2004. The main pollutant was to-tal phosphorus (TP) in Lake Dongting. Water quality was worse in the flood water season than in the other waterseasons, but after 2002,water quality was worse in the flood water season had been better than in the normal water season.The water pollution could be more~in the entering riverways than in the lake bodies of Lake Dongting spatially. Water quality in Lake Weat Dongting was worst, in lake South Dongting was worse, and in Lake East Dongtingwas not polluted badly.