Abstract:A monoclonal antibody (MAb) against norfloxacin was prepared using hybridom a techniques, and indirect competitive Fluorescence immunoassays for norfloxacin (NFLX) was established successfully. The regression equation was I=31.92logC-5.0083 (r= 0.9965) with the limit of detection about 6.09 μg/L. The linear detection was ranged well from 10μg/L to 500μg/L. The cross-reaction tests indicated that most structurally related phenolic compounds did not interfere with the analysis of NFLX. The anti- NFLX antibody had excellent recognition specificity to NFLX. The result developed in this study indicates this method would practicable to detection norfloxacin residues in animal derived food.