OBJECTIVE： To establish the method for content determination of the related substance in fudosteine raw material and its preparations. METHODS： Fudosteine or its preparations produced by 8 domestic enterprises were taken as samples. HPLC method （external standard） was used to determine the contents of impurities A， B and C. The separation was performed on MGⅡ C18 column with mobile phase consisted of 0.12％ sodium hexane sulfonate solution （pH 2.0） at flow rate of 1.0 mL/min. The detection wavelength was set at 210 nm， column temperature was 35 ℃ and sample size was 20 μL. The contents of impurities E， F， G were determined by HPLC method （principal component self-contrast method with correction factor）. The separation was performed on Altech Altima C18 column with mobile phase consisted of 0.05 mol/L phosphate buffer-acetonitrile- water （gradient elution） at the flow rate of 0.5 mL/min. The detection wavelength was set at 200 nm， and the column temperature was 30 ℃. The sample size was 20 μL. RESULTS： The linear ranges of impurity A， B， C， E， F and G were 0.446-22.291， 0.202-20.158， 0.101-12.082， 0.111 0-11.100， 0.210 4-10.520， 0.221 6-11.080 μg/mL， respectively. The limits of detection were 5.57， 1.01， 1.99， 2.22， 4.21， 4.43 ng， respectively. The limits of quantitation were 11.14， 2.02， 3.98， 4.45， 8.42， 8.85 ng， respectively. The relative correction factors of impurities E， F and G were 0.91， 1.42 and 1.73， respectively； their relative retention time were 0.88， 1.95 and 3.08. RSDs of precision （n＝6） and stability [impurity A （4 h，n＝3）， other impurities （24 h，n＝7）] tests were all lower than 2.0％. The average recoveries were 98.0％， 97.3％， 102.4％， 99.4％， 98.9％， 96.4％， respectively； RSDs were 1.4％， 1.5％， 1.1％， 0.9％， 1.2％， 0.5％ （n＝9）， respectively. Total contents of substances in fudosteine raw material or its preparation produced by 8 enterprises were all lower than 1.1％. CONCLUSIONS： Established method is sensitive and specific. The method can be used for the quantitative study on related substances in fudosteine raw material and its preparations．