Abstract: Based on the sensitizing action of cetyltrimethylammonium bromide (CTMAB) on the fluorescence intensity emitted by the reaction system of moxifloxacin (MXFX) and Y(Ⅲ) in a citrate buffer solution of pH 5.00, a fluorophotometric method for determination of residual amount of MXFX in milk was proposed. Linear relationship was found between values of average relative fluorescence intensity, If measured at wavelengths of 292 nm (λex) and 483 nm (λem) and concentration of MXFX in the range of 50-800 μg·L-1. Limit of detection (3σ) found was 46.2 μg·L-1. The proposed method was used in the determination of MXFX in samples of milk, giving values of average recovery of 92.8%, and of RSD′s (n=5) less than 3%.