Abstract： Objective To determine 9 impurities in doxofylline injection by high performance liquid chromatography(HPLC).Methods A CAPCELL PAK C18 ME column(4.6 mm×250 mm,5 μm)was used.Acetonitrile-phosphate buffered saline was used as the mobile phase,with gradient elution.The flow rate was 1.0 mL·min-1,the column temperature was 30 ℃,and the detection wavelength was 273 nm.Nine possible impurities in doxofylline injection were quantitatized and the limit was checked.Results Under these conditions,the 9 impurities were completely separated,with recoveries between 97.0％～105.0％.Conclusion This method is specific and reproducible,and can be used for the determination of related substances in doxofylline injection.