Abstract: In order to investigate the water environment in Jiangsu section of the Changjiang River and provide reference for water environmental protection, according to the survey results of periphyton in 13 sampling points in the region, non-parametric test and redundancy analysis were used to analyze the spatial and temporal distribution characteristics of periphyton, and random forest was used to reduce the dimension of physical and chemical indexes of water, and Qr index, IBI and biodiversity index were used to evaluate the river health.The results showed that the periphyton in Jiangsu section of the Changjiang River were mainly Cyanobacteria,green algae and diatoms, and there was no significant difference in community structure(P>0.05).25 functional groups were detected in the basin, and their succession rules were as follows: B+Lo+MP+N+P+W1(summer) →Lo+MP+N+P(winter).Redundancy analysis showed that the driving factors affecting algae in summer were potassium permanganate index, ammonia nitrogen and phosphate, and in winter were electrical conductivity, potassium permanganate index, turbidity and dissolved oxygen.The results of river health evaluation show that the water environment is satisfactory in basic, and the middle section is the best.