Abstract: A solid phase extraction-high performance liquid chromatography tandem mass spectrometry (SPE-HPLC-MS) method was used to monitor six classes and 21 types of antibiotics in the surface water of Zhucao River-Daxi Reservoir of Lake Taihu Basin for one year. The study aimed to analyze their occurrence characteristics, study their relationship with environmental factors, trace their sources, and evaluate their potential risks. The results showed that a total of 19 target antibiotics were detected in the study area, in which tetracyclines, quinolones, and sulfonamides were the main types of antibiotics. Temporally, except for sulfonamides, which were high in summer and low in winter, the other antibiotics were basically high in winter and low in summer, with similar trends both in spring and autumn. Spatially, the distribution pattern of the antibiotic concentration generally showed: reservoir bank zone>inflow tributary estuary>Zhucao River. Correlation analysis showed that there were significant correlations between the antibiotics and environmental factors, including water temperature, DO, pH, COD_Mn, Chla and nutrients. Principal component analysis-multiple linear regression (PCA-MLR) analysis showed that the antibiotics in Zhucao River-Daxi Reservoir mainly came from livestock breeding wastewater, agriculture wastewater and aquaculture wastewater. Ecological risk assessment showed that most single antibiotics were risk-free to algae, but roxithromycin, enrofloxacin, norfloxacin, and sulfamethoxazole were at risk to algae, in which norfloxacin and enrofloxacin were even at medium risk. In winter, spring, summer and autumn, the proportion of sites with total risk of algae exposure to 19 kinds of antibiotics was 95.7%, 73.9%, 73.9% and 91.3%, respectively, among which 56.5%, 34.8%, 39.1% and 47.8% of the sites were even at medium risk. At the same time, the total risk of Daxi Reservoir was greater than Zhucao River, with winter greater than summer. The total ecological risk of algae was mainly from quinolones, while that of invertebrates and fish was mainly from sulfanilamides. Meanwhile, all the target antibiotics had no potential health risks to the human body.