An investigation was performed for the simultaneous determination of norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), and ofloxacin (OFL). The developed method was successfully applied to analyze the fate of Fluoroquinolones (FQs) in water treatment processes. Four FQs were found in Yangtze River, Taihu Lake, Dasi Reservoir, Songhua River, and drinking water treatment processes of A,B and C in Jiangsu. Analyses of samples from Yangtze River, Taihu Lake, Dasi Reservoir and Songhua River indicated that FQs were present at concentrations of 51-9,5-4,2-248 and 61-165 ng／L, respectively. FQs residues in water treatment processes show that the removal efficiency of conventional water treatment processes is between 20％ and 40％, and the coagulation-sedimentation process plays a dominant role. The removal efficiency of ozone-activated carbon process is about 20％-60％.