A process for purifying the compound of formula I, comprising the steps of: 1) pre-treatment of swine bile by dissolving swine bile solid derived from swine bile, containing the mixture of chenodeoxycholic acids of Formulae I-IV, and having 35-55 wt% of chenodeoxycholic acid content, in organic solvent containing salt, wherein the organic solvent is ethyl acetate or acetone, and the salt is at least one selected from the group consisting of sodium chloride, anhydrous magnesium sulfate and anhydrous sodium sulfate; 2) esterification of a mixture of chenodeoxycholic acids of formulae I to IV by adding C 1-4 alcohol to the residue obtained from step; 3) acetylation of the mixture of esters of chenodeoxycholic acids of formulae I to IV by adding anhydrous acetic acid and a weak base selected from anhydrous sodium acetate or pyridine to the residue obtained from step; 4) adding non-polar organic solvent selected from hexane, heptane, octane or isooctane to the residue obtained from step and stirring under reflux until all the residue is dissolved, and subsequently crystallizing and removing the acetylated esters of chenodeoxycholic acids of formulae III to IV, and a part of the acetylated ester of chenodeoxycholic acid of formula II; 5) adding C 1-4 alcohol to the residue obtained from step and crystallizing the compound of formula V for 2~3 hours at the temperature range of 20 ~ 25°C; and 6) deprotection of the compound of formula V obtained from step by adding water and base selected from sodium hydroxide or potassium hydroxide to the compound of formula V, and crystallization of the compound of formula I in the presence of water by adding acid selected from hydrochloric acid or sulfuric acid. 1) pre-treatment of swine bile by dissolving swine bile solid derived from swine bile, containing the mixture of chenodeoxycholic acids of Formulae I-IV, and having 35-55 wt% of chenodeoxycholic acid content, in organic solvent containing salt, wherein the organic solvent is ethyl acetate or acetone, and the salt is at least one selected from the group consisting of sodium chloride, anhydrous magnesium sulfate and anhydrous sodium sulfate; 2) esterification of a mixture of chenodeoxycholic acids of formulae I to IV by adding C 1-4 alcohol to the residue obtained from step; 3) acetylation of the mixture of esters of chenodeoxycholic acids of formulae I to IV by adding anhydrous acetic acid and a weak base selected from anhydrous sodium acetate or pyridine to the residue obtained from step; 4) adding non-polar organic solvent selected from hexane, heptane, octane or isooctane to the residue obtained from step and stirring under reflux until all the residue is dissolved, and subsequently crystallizing and removing the acetylated esters of chenodeoxycholic acids of formulae III to IV, and a part of the acetylated ester of chenodeoxycholic acid of formula II; 5) adding C 1-4 alcohol to the residue obtained from step and crystallizing the compound of formula V for 2~3 hours at the temperature range of 20 ~ 25°C; and 6) deprotection of the compound of formula V obtained from step by adding water and base selected from sodium hydroxide or potassium hydroxide to the compound of formula V, and crystallization of the compound of formula I in the presence of water by adding acid selected from hydrochloric acid or sulfuric acid.