Abstract: By applying the fluorescence microscopic imagery and using the Ca2+-ion sensitized minocycline fluorescence reaction system,a method for determination of residual amount of minocycline in milk was proposed.The fluorescence reaction mixture was prepared by mixing the minocycline solution with definite amounts of CaCl2 solution,pH 8.50 ammoniacal buffer solution and PVA-124 solution.After reacting for 10 min,a drop of the mixed solution was dropped onto the hydrophobic glass slide,and after volatilization of the solvent by microwave heating,a capillary fluent self-ordered ring with its diameter of 1.7 mm and ring belt width of 45.3 μm was formed.When the volume of sample droplet taken was 0.3 μL,the linearity range of minocycline found was between 5.6×10-13-1.8×10-11mol,and the detection limit (3σ) found was 5.6×10-14mol.The proposed method was applied to the determination of minocycline in minocycline capsules and of residual amounts of minocycline in milk,giving values of recovery in the ranges of 104.3%-105.0% and 96.0%-105.9% with RSD′s (n=5) less than 3.5%.