Abstract: The composition and function of bacterial communities in lake water and sediments are of significant importance for material cycling and environmental health in urban lakes. We focused on the water and sediment of Zilang Lake. Thirteen sampling points (S01-S13) were set up in the lake area to collect water samples (WS) and sediment samples (SS) from six points in autumn. Characteristics of microbial communities and their driving factors were analyzed and metabolic functions of bacterial communities were predicted based on Tax4Fun. The results showed significant differences in the composition of bacterial communities between water and sediment. Bacterial diversity indices in sediment were higher than in water, with seven dominant phyla (relative abundance>5%) in sediment compared to four in water. Additionally, due to the shallow depth and limited sediment at sampling point 8, the bacterial community composition and functions in both WS08 and SS08 samples were significantly different from other sampling points. Key environmental factors influencing bacterial community composition in water were available phosphorus (AP), pH, and electrical conductivity (EC), while in sediment, significant environmental factors were AP, total organic carbon (TOC), and pH. Metabolic functional analysis of bacteria indicated that amino acid metabolism and carbohydrate metabolism were the main functions in the lake ecosystem. Furthermore, their relative abundances in water were higher than in sediment, although the difference was smaller compared to sediment. The results of this study contribute to understanding the current distribution and function of bacteria in early-stage urban artificial lake water and sediment, providing a theoretical basis for nutrient enrichment warning and environmental monitoring in urban lakes.