The invention relates to the technical field of a Delafloxacin purifying method . The Delafloxacin purifying method comprises the following steps: adding Delafloxacin to a polar aprotic solvent, heating, stirring until Delafloxacin is dissolved, adding distilled water, and gradually cooling for crystallizing to obtain highly pure Delafloxacin. Delafloxacin prepared by present synthetic methods needs purification, the preparation using a simple column chromatography mode increases the large scale production difficulty and greatly increases the preparation cost. The method can effectively remove impurities, and makes the compound Delafloxacin have a high purity (above 99.0%) and meet subsequent preparation demands.