Abstract: After the Wenchuan earthquake, the piedmont riverbed of the Shiting River was seriously eroded, which had an important impact on the river ecology.However, there is few quantitative ecological evaluation of the piedmont scouring reach.We investigated community structure of macroinvertebrate and environmental factors at 18 sampling sites of the Shiting River, Mianyuan River and Qianjiang River from autumn 2021 (October) and summer 2022 (July), where the piedmont riverbed is severely eroded since the Wenchuan earthquake.We analyzed the seasonal variation characteristics of the macroinvertebrate community structure, diversity parameters, functional feeding groups, and functional habit groups.Results showed that a total of 54 species of benthic animals were collected from the Shiting River, belonging to 4 phyla, 6 classes, and 35 families in autumn.In summer, a total of 33 species of benthic animals were collected, belonging to 1 phyla, 1 class, and 18 families.In autumn and summer, the collector-gatherers were the group with the greatest dominance, while the predators had the smallest dominance.In autumn, the dominance of the clingers was the highest.The dominance of the sprawlers was the highest in summer.The dominance of climbers was the lowest in both autumn and summer.The multi-metric index (MMI) evaluation system established based on the macroinvertebrate assemblage indices evaluated the ecological qualities of three rivers' habitat patches.According to the system, the ecological quality can be divided into five levels (bad, poor, moderate, good and perfect).The ecological qualities of the habitat patches of the three rivers were generally good, with several patches being moderate.The riverbed erosion of the Mianyuan River and Jianjiang River was relatively small, and their overall ecological quality of habitat patches was higher than that of the Shiting River.In autumn, the ecological qualities of habitat patches in the Shiting River were better than that in summer.