Xiangxi River originates from the Shennongjia Forest region and is the largest tributary in the Hubei portion of the Three-Gorge Reservoir. The hydropower resource is abundant in Xiangxi River, and hydropower stations are usually connected sequentially. A cascade of three reservoirs (Gudongkou Reservoir 1, Gudongkou Reservoir 2 and Xiangxi Bay of the Three-Gorge Reservoir) in Xiangxi River Basin was selected to investigate macroinvertebrate ecology in a reservoir cascade system. Principal Components Analysis (PCA) was applied to analyze the water quality of the three reservoirs. The result implies that the water quality was degrading along the cascade of reservoirs. Non-metric Multidimensional Scaling (NMS) was used to analyze the differences among benthic communities. It indicates that sampling stations located in the lacustrine zone of a reservoir are representative for comparing macroinvertebrate assemblages along a reservoir cascade. Oligochaetes were numerically dominant both in Gudongkou Reservoir 1 and Xiangxi Bay, and chironomids were dominant in Gudongkou Reservoir 2. Similar pattern was also exhibited in species composition. However, the benthic assemblages of the three reservoirs were all dominated by pollution-tolerant taxa in spite of their differences in water quality. Relationship between the community structure and environmental variables was studied by using Canonical Correspondence Analysis (CCA) to determine which variables contribute most to differences in community structure. It discloses that turbidity influenced the benthic assemblages significantly. TOC/Turb was applied to determine the influence of organic matter on turbidity. The ratio of Gudongkou Reservoir 2 was the lowest among the three reservoirs, which implicates that the influence of organic matter on turbidity was smaller in Gudongkou Reservoir 2 than those in the other two reservoirs. This suggests that inorganic matter such as suspended silt and clay grains contribute substantially to the turbidity of Gudongkou Reservoir 2.