This study examines the small and medium-sized rivers in Shanghai to investigate the effects of various land use types, namely residential, agricultural, commercial, and industrial, on the characteristics of phytoplankton communities and water quality parameters. Through a combination of field sampling and laboratory analysis, which emcompasses phytoplankton community structure (including species composition and diversity indices) as well as water quality parameters (such as pH, conductivity (Cond), total suspended solids (TSS), chlorophyll-a (Chla), total nitrogen (TN), and total phosphorus (TP)), the correlation between land use types and phytoplankton community characteristics is elucidated. The results indicate that rivers situated in residential areas are predominantly characterized by Cryptomonas, displaying elevated nutrient concentrations, increased biomass, yet reduced diversity. In agricultural regions, the phytoplankton community is primarily represented by Synura, whereas in industrial and commercial zones, Telcaulax emerges as the dominant species. The types of land use surrounding the rivers significantly influence the diversity indices of phytoplankton(p<0.05) as well as the richness of OTUs as measured by the Chao index (p<0.05). Redundancy Analysis (RDA) indicates that TN, TSS, pH, Chla, and Cond significantly (p<0.05) impact the composition of phytoplankton communities. The genera Synura, Plagioselmis, and Mallomonas warrant further investigation as potential indicator species. This study establishes a scientific foundation for the ecological restoration and water quality management of small to medium-sized rivers in Shanghai.