Antibiotic concentrations in the five urban lakes in Nanchang City were monitored with methods of solid phase extraction and high performance liquid chromatography tandem mass spectrometry. The sources of antibiotics were analyzed and ecological risk of typical antibiotics on fish, invertebrates and algae were assessed using Risk Quotients (RQs). Results showed that, the detected concentration range of tetracyclines, sulfonamides, quinolones, lincomycin and macrolides were ND-6.3 ng/L, ND-32.0 ng/L, ND-97.2 ng/L, ND-54.7 ng/L and ND-98.4 ng/L, respectively. Erythromycin and lincomycin were the main antibiotic types in the lakes. The antibiotic concentration detected in the five lakes were in the medium level compared with other lakes. The detected concentration of enrofloxacin was relatively higher than that in other lakes. RQs of the six main detected antibiotics were all less than 0.1, indicating the lowest ecological risk. The main ecological risk factors of the five lakes were erythromycin, sulfadimidine, roxithromycin, erythromycin and sulfadiazine respectively in Lake Aixi, Lake Yao, Lake Qingshan, Lake Xiang and Lake East-west. This study provides basis for water environment management, especially for controlling emerging pollutants in such urban lakes.