Method for preparing obeticholic acid intermediate

The invention discloses a method for preparing an obeticholic acid intermediate 3-alpha-hydroxyl-6-ethylidene-7-keto-5-beta-cholanic acid (I) by taking 7-oxo-lithocholic acid (II) as a raw material as well as its derivative (IA). According to the invention, 7-oxo-lithocholic acid (II) is protected or directly unprotected through 3-hydroxy or 3-hydroxy and 24-hydroxy, the is further subjected to an aldol condensation reaction with acetaldehyde to obtain the 3-alpha-hydroxyl-6-ethylidene-7-keto-5-beta-cholanic acid (I) and the derivative, and the method is used for preparing the obeticholic acid. The method has the advantages of simple process and high yield, and is suitable for industrial production.