NOVELTY - Preparing hyodeoxycholic acid involves leftover salting out, adding leftovers of bilirubin to kettle, then adding water, adjusting pH value to 2-4, adding salt, filtering to obtain filter cake; adding cake in kettle and hydrolyzing; adsorbing for decoloring; filtering, steaming, vacuum drying to obtain crude product of hyodeoxycholic acid; esterifying; performing column chromatography; carrying out gradient elute with eluent; reducing pressure; hydrolyzing; adding hyodeoxycholic acid in organic solvent, purifying to obtain crystals of hyodeoxycholic acid; and vacuum drying.    USE - For preparing hyodeoxycholic acid (claimed), used in biological pharmacy.    ADVANTAGE - The process provides hyodeoxycholic acid having high purity, and free from extraneous odor; is environment-friendly, uses recyclable solvent, and easy to operate; and has low cost, and simple and safe operation.    DETAILED DESCRIPTION - Preparing hyodeoxycholic acid involves salting out, taking leftovers of bilirubin as raw material, adding to reaction kettle, then adding water to the reaction kettle, adjusting the pH value to 2-4 with acid solution, controlling temperature of 15-25 degrees C, adding salt while stirring, keeping on stirring, filtering to obtain a filter cake; adding the filter cake in reaction kettle, then adding alkali liquor for hydrolyzing for 30-60 minutes, acidifying with acid solution until Congo red turns blue, standing, filtering to obtain a filter cake; adsorbing for decoloring: adding the filter cake obtained at above step to reaction kettle, then adding organic solvent and activated carbon in the reaction tank, heating to 65-80 degrees C, condensing to backflow for 30-60 minutes, cooling to 20-30 degrees C, filtering to obtain filtrate, adding dehydrating agent to the filtrate, dehydrating for 15-24 hours; filtering, steaming the filtrate, concentrating, standing for crystallizing, collecting the crystals, vacuum drying to obtain the crude product of hyodeoxycholic acid; dissolving the crude product of hyodeoxycholic acid in an organic solvent, adding concentrated sulfuric acid for esterifying, stirring for 36-48 hours at 15-25 degrees C, adjusting pH value to 6.8-7.2, keeping on stirring for 1-2 hours, filtering, washing the filter cake with an organic solvent for 2-3 times, merging the filtrates and washing solutions, reducing pressure and steaming to remove organic solvent to obtain brown thick matter; monitoring via thin layer chromatography (TLC); performing column chromatography; packing via a wet process; adding the brown thick matter in silicagel column; carrying out gradient elute with eluent, collecting the eluate, monitoring via TLC; the reducing pressure for concentrating to obtain faint yellow thick solid; hydrolyzing by adding the faint yellow thick solid to a reaction kettle, adding alkali and water, adjusting the pH value with acid solution until the Congo red turns blue, filtering, collecting precipitate, washing with water until the effluent is colorless to obtain the hyodeoxycholic acid; purifying by adding the hyodeoxycholic acid in an organic solvent, mechanically stirring to heat until the organic solvent is boiling, after the hyodeoxycholic acid is dissolved, adding water in batches, keeping on stirring, after the temperature is cooled to 10-20 degrees C, mechanically stirring for 30-60 minutes, filtering to obtain crystals of hyodeoxycholic acid; and vacuum drying the crystals with a constant temperature vacuum drying box to obtain the pure product of hyodeoxycholic acid.