The carbon and nitrogen stable isotope analysis have been used to study the aquatic ecological system and trophic ecology since the early 1970s. With the increasing of human activities, many kinds of pollution, such as industrial waste water, widespread pollution from the overuse of fertilizers, and domestic sewage and rubbish, were discharged into rivers and lakes, causing aquatic eutrophication, which has resulted in many severe ecological consequences like the disappearance of aquatic plants and the decrease in biodiversity. Therefore, it is vital to monitor the eutrophication as early as possible. The carbon and nitrogen stable isotope analysis are a good method of checking and evaluating the trophic conditions of aquatic ecology. Moreover, many studies were conducted with regard to the organic materials in human sewage as well as the influences of the input of nutrient materials on the aquatic ecology environment. And the organisms of the Hanfeng Lake have been also faced with the threats of domestic sewage water and widespread pollution from the overuse of fertilizers produced by surrounding residents. In the present study, the stable isotope approach was used and we compared the difference of isotopic signatures of the same species between the impacted areas (A and B sites) and the control areas (C and D sites).. So the aims of the present study were trying to investigate the effects of human sewage and agricultural non-point source input in organisms from the different trophic levels (primary producers and primary consumers) in the Hanfeng Lake, an upper reaches of the Yangtze River. The results showed that the carbon and nitrogen stable isotope values of POM and sanil samples were various in different groups. In impact groups, the values of POM samples were -25.93‰ --24.63‰ forδ¹³C and 4.12 ‰ -9.86‰ for δ¹⁵N, the values of snail samples ranged from -14.28‰ - -21.60 ‰ (δ¹³C) and 7.97 ‰ - 19.99‰ (δ¹⁵N); In control groups, the values of bothe POM and snails samples were -25.62- -22.51‰ (δ¹³C)、0.01-6.56‰ (δ¹⁵N),-22.96--19.21‰ (δ¹³C)、6.75-8.89‰ (δ¹⁵N), respectively;.The δ¹³C values for either POM and snails (primary consumers) were not significantly different between different sampling groups (P>0.05), while the change of δ¹⁵N in different sampling groups varied greatly (P<0.05). The relative trophic position of primary producer, such as periphytic algae, POM (mainly composed of phytoplankton) and primary consumers (snails), are higher in impact groups than in those of control groups, whereas there is no significant difference in the relative trophic levels of the other higher trophic level consumers, such as carp (Cyprinus carpio), crucian (Carassius auratus) and Amur catfish (Silurus asotus). Therefore, the nitrogen stable isotope signature was proved to better describe the information on the absorption and enrichment of anthropogenically derived material in food webs of the Hanfeng Lake. Compared with the other organisms(e.g. periphytic algae and fish), POM and snails were more sensitive to pollution than other species, and could be more appropriate to serve as an indicator of assessing the quality of environment. Moreover, the organisms from both impacted groups (site A and site B) in the Hanfeng Lake have been profoundly influenced by anthropogenic inputs of nutrient matter, and site B received a more stronger interference than site A. In conclusion, it has important significance to strengthen the protection of the environment of the Hanfeng Lake, and control the effluent discharge amount for protecting the water quality of the Xiaojiang River and even the Three Gorges Reservoir Area.