Abstract: A pre-column derivatization high performance liquid chromatography (HPLC) method was established to determine residual content of taurine in taurodeoxycholic acid (TUDCA) drug substance. The samples were treated with pre-column derivatization reagent 9-fluorenylmethyl chloroformate (FMOC-Cl). The derivative reaction products were then separated by HPLC using reverse phase C18 column, and gradient elution with mobile phase citric acid - sodium citrate buffer (A) and methanol - acetonitrile - citric acid-sodium citrate buffer (B). The UV detection wavelength was 264 nm. By the method, trace amount of taurine could be well separated at baseline level from the other related substances in taurodeoxycholic acid sample. The linear correlation coefficient r between peak area and taurine concentration was 0.9995 in the range of 0.31 ～ 41 μg/mL. The limit of detection was 0.1 μg/mL. The recovery was found between 98.8% ～ 100.5%. The method has been applied in real samples analysis and shown sensitive, reproducibly, and suitable for detecting residual content of taurine in taurodeoxycholic acid.