Abstract: Based on the water quality monitoring data of the adjacent mainstream of Three Gorges Reservoir and Xiangxi Bay from July 2003 to July 2013, using Carlson trophic status index and Evaluation method of two-dimensional coordinate system for Carlson trophic status difference. We described their trophic level in the past 10 years before and after the impoundment of Three Gorges Reservoir, the trophic status of the water body and its limiting factors are evaluated. And the relationship between the trophic status and the hydrodynamic conditions in the mainstream and tributary streams was established to determine whether the hydrodynamic conditions on the main and tributary streams were the limiting factor of eutrophication. The results showed that the trophic status of Three Gorges Reservoir had not shown a significant upward or downward trend in the past 10 years. In Three Gorges Reservoir, the hydrodynamic conditions of the mainstream of the Yangtze River had little control effect on nutrient utilization. Different from the mainstream of Three Gorges Reservoir, the hydrodynamic conditions in the tributary Xiangxi Bay could affect the utilization of nutrients by algae to a certain extent, which indicated that we could control algal blooms by adjusting the hydrodynamic conditions of the tributary Xiangxi Bay.