The overuse and continuous input of antibiotics lead to their significant accumulation in aquatic environments， which poses a potential threat to aquatic ecosystems and human health. The spatial and temporal distribution of 38 antibiotics in the waters and sediments of Yongjiang River Basin （YRB） as well as the corresponding ecological risks were analyzed. The results showed that there were significant differences in the species and concentrations of antibiotics in surface water and sediments during different hydrological periods. The average level of antibiotics in the flood season （471.8 ng·L-1） was much higher than that in the normal season （150.7 ng·L-1） and dry season （133.3 ng·L-1）. The antibiotic levels in the sediments decreased following the order of normal season （227.7 ng·g-1） > dry season （165.6 ng·g-1） > flood season （90.3 ng·g-1）. From the perspective of spatial distribution， the average concentration of antibiotics in the tributary （170.0-521.5 ng·L-1） was higher than that in the main stream （111.5-431.4 ng·L-1）， and the maximum contribution of antibiotic pollution came from the Liangfengjiang tributary. Based on the ecological risk entropy assessment， ofloxacin， enoxacin， and norfloxacin in YRB exhibited higher risk to algae. Lomefloxacin posed a high risk to aquatic invertebrates. The presence of antibiotics in YRB posed a certain extent ecological risk.
Keywords: Yongjiang River Basin（YRB）; antibiotics; ecological risk; sediment; water body.