Abstract: Zooplankton, as a critical component of aquatic ecosystems, exhibits high sensitivity to external disturbances and aquatic environmental changes. Analyzing the composition of zooplankton communities across different hydrological periods in reservoir ecosystems is essential for understanding the dynamic changes of reservoir ecosystems and providing a scientific basis for reservoir management. Based on data from two sampling surveys conducted in Luhun Reservoir in 2025, it analyzed the species composition, density, biomass, and diversity characteristics of zooplankton communities during different hydrological periods. Combined with Pearson correlation analysis and redundancy analysis, the key factors influencing the composition and distribution of zooplankton communities were explored. The results showed that a total of 48 zooplankton species were detected in Luhun Reservoir, including 21 rotifer species, 13 cladoceran species, and 14 copepod species, with rotifers as the dominant group. The relative density of rotifers accounted for a large proportion (69.45% in the dry season and 72.98% in the wet season). The species richness, density, Simpson diversity index, Shannon-Wiener diversity index, and Margalef richness index in the wet season were significantly higher than those in the dry season, while the biomass in the wet season was significantly lower than that in the dry season. The main environmental factors affecting the zooplankton community were DO concentration, EC, CODMn, and TN concentration in the dry season, and pH value and TN concentration in the wet season.