Periphytic algae are sensitive to the changes of aquatic environment and can reflect the health status of water quality quickly. In this study, the community structure and water environment characteristics of algae around the Irtysh River were investigated systematically in 2019, and the biological integrity index of periphytic algae was used to evaluate the ecological health. The results showed that there were 102 species of algae belonging to 41 genera and 6 phyla, mainly Bacillariophyta. The temporal change of density and biomass for periphytic algae was September > July > May, and the spatial distribution was middle and lower reaches > upstream, tributaries > trunk stream. Principal component analysis (PCA) and canonical correspondence analysis (CCA) showed that the main environmental factors affecting the community structure of peripheral algae were water temperature, dissolved oxygen, permanganate index, ammonia nitrogen, nitrate nitrogen, pH and suspended matter. The average values of algal diversity index (H'), richness index (D) and Pielou evenness index (J) around the Irtysh River were 3.52, 3.02 and 0.75, respectively, indicating that the overall water quality of the Irtysh River basin is pollution-free or non-pollution. the results of P-IBI analysis showed that 5 sampling sites were healthy, 1 sampling site was sub-healthy, 3 sampling sites were general, and 1 sampling site was very poor, suggesting that the overall ecological health of the Irtysh River tended to be good. The results of this study can provide an effective measure for aquatic environment monitoring of Irtysh River and, meanwhile, provide basic data and theoretical references for the ecological protection of Irtysh River basin.