The Xiaojiang River Basin is a typical dry-hot valley area, characterized by high temperatures, little rain and many debris flow gullies, where ecological environment is very fragile. In April and September of 2017, field surveys were conducted in the five debris flow gullies (i.e., the Diaoga Creek, the Jiangjia Creek, the Lanniping Creek, the Qingshui Creek, and the Taojiaxiaohe Creek) and the Xiaojiang River. The purpose of this study is to understand fluvial geomorphological feature, water environment, and macroinvertebrate communities in the five debris flow gullies and the Xiaojiang River, to analyze the differences in macroinvertebrate communities among debris flow gullies with different riverbed structures, and to reveal the responses of macroinvertebrates to the fluvial geomorphological parameter (degree of concavity-convexity) reflecting the development degree of riverbed structure. A total of 70 taxa of macroinvertebrates were identified, belonging to 4 phyla, 6 classes, 38 families and 69 genera. With regard to the taxonomic groups, arthropods were dominant in the species richness, density, and biomass of macroinvertebrates in the five debris flow gullies and the Xiaojiang River, accounting for 78.0%-92.5%, 98.7%-100.0% and 65.0%-100.0% of the total richness, densities, and biomass, respectively. With regard to the functional feeding groups, collector-gatherers were all dominated in the five debris flow gullies and the Xiaojiang River, accounting for 74.3%-96.3% of the total densities. Regression analyses showed that the species number, density, and biomass of macroinvertebrates were all positively correlated with the fluvial geomorphological parameter (degree of concavity-convexity) of the five debris flow gullies. The present study indicated that the well-developed riverbed structure plays an important role in maintaining the stability of the fluvial geomorphology and ecological quality. The results of this study can provide scientific basis for riverbed structure reconstruction and ecological restoration of debris flow gullies in mountain regions of the Xiaojiang River Basin.