The occurrence of 22 antibiotics, including eight quinolones, nine sulfonamides and five macrolides in water and sediment from Zizhuyuan Lake has been investigated in Beijing, China. Sediment samples were extracted by pressurized liquid extraction (PLE). Aqueous extracts from PLE and water samples were concentrated by solid-phase extraction (SPE) and detected by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS). Antibiotics were detected in concentrations of up to 20 ng/L in water samples and 52.1 μg/kg in sediments. Quinolones were the most prevalent contaminants in water body, accounting for 63.4%, while quinolones and macrolides were prominent in sediments, accounting for 55.1% and 41.7%, respectively. The environmental risk assessment revealed that some antibiotics, in particular Ofloxacin (OFL) and Sulfamethoxazole (SMX), could cause high damage to algae and plants in the aquatic ecosystem.