Abstract:The changes of microorganisms in the Three Gorges Reservoir area affect the function of freshwater ecosystems and human health. In March 2018, a microbiological investigation was conducted on different soil samples on both sides of the Wanzhou Second Bridge. The drying method and the potassium dichromate volumetric method were used to analyze the physical and chemical properties of the soil, the plate dilution coating method was used to analyze the number of cultivable microorganisms, the composition and diversity of soil microbial communities were analyzed by 16S rDNA gene sequencing and phylogenetic trees. The results show that there are differences in the organic matter content of different sedimentary soils, and the number of microorganisms ranks in the sequence of bacteria> actinomycetes> fungi. Bioinformatics analysis found that the bacteria were mostly Pseudomonas and Acinetobacter. Therefore, this study provides an early warning for environmental pollution in the Three Gorges Reservoir area and will play an important role in the rational use and management of the ecological environment in the Three Gorges Reservoir area in the future.