Abstract: The effective method of removal the remaining active ingredient in oxytetracycline residues is studied. The influence of hydrochloride acid, calcium oxide, methanol and heating temperature on the removal of the remaining ingredient in oxytetracycline residue is investigated. In the process, the residue is firstly immersed by 2.0 mol/L HCl with mechanical stirring in a water bath of 95 ℃, and then it is cooled to room temperature accompany with adding methanol, mechanical stirring and leaching reaction solution. The filter residue is mixed by adding distilled water, adjusting the pH to 5.0 by CaO, stirring in a water bath of 95 ℃ and filtering, and then the filter residue is dried at 95 ℃. The average result of oxytetracycline residues titer after treated is 430.0 U/g and the elimination factor is 96.9%.

Key words: oxytetracycline residues, active ingredient, remaining