The Jinsha River basin has been marked as an ecological shelter and functional critical region of the upper Yangtze River. It undertakes a variety of important functions, including biodiversity conservation. However, studies on the species composition and community structure of macrozoobenthos in this region are still very limited. To systematically understand the composition and resource status of macrozoobenthos in the lower Jinsha River and to explore the main environmental factors affecting the community structure, the macrozoobenthos of 16 sites in the riparian zone of the mainstream and its tributaries within the four cascade reservoirs along the lower Jinsha River were surveyed three times in 2017?2018. A total of 63 taxa of macrozoobenthos were recorded, and the species composition was mainly aquatic insects, accounting for 66.7% of the total taxa. The number of taxa was between 1 and 22 among the sampling sites. In terms of different reservoir areas, it was the highest within the Wudongde reservoir area and the lowest within the Xiluodu reservoir area. Among different seasons, it was the highest in summer and the lowest in winter. Hydropsyche sp. had the highest dominance among the species, and the dominant species differed across the seasons. The mean density and biomass of macrozoobenthos were (201.6±306.1) ind./m² and (3.2±5.5) g/m² , respectively, with significant differences in different reservoir areas. The CCA (canonical correspondence analysis) results showed that the key affecting factors of macrozoobenthos community composition in the lower Jinsha River were substrate (Sub), water velocity (WV), elevation (Ele), and dissolved oxygen (DO). In general, the macrozoobenthos community structure of the lower Jinsha River was dominated by aquatic insects and Annelida, with lower density and biomass than other rivers in this region. Due to the fast flow velocity and simple habitat bottom in the mainstream, the macrozoobenthos were generally not high in species number or standing crop. However, the rich macrozoobenthos resources in the tributaries of the interval play an important role in maintaining regional biodiversity. Based on the results, several suggestions for the environmental protection of the lower Jinsha River were provided, i.e., meeting the conservation challenges necessitate long-term monitoring of aquatic organisms and impact assessment of aquatic ecology, protecting the riparian zone of rivers to support the river habitat diversities and coordinating the protection of mainstream and tributaries of the lower Jinsha River aimed at maintaining the integrity of the river ecological network. ＜/