NOVELTY - Preparing eplerenone, comprises e.g. taking androstenedione and introducing hydroxy group to obtain 9(R)-hydroxy-androstenedione (II), carrying out dehydration and etherification to obtain 3-ethoxy-3,5,9(11)-androst-trien-17-one (IV), carrying out epoxidation, condensation and decarboxylation of (IV) to obtain 17 beta -hydroxy-3-oxo-pregna-4,9(11)-dien-21-carboxylic acid- gamma -lactone (V), then substituting methylfuran to obtain 7 alpha -(5-methyl-2-furanyl)-17 beta -hydroxy-3-oxo-pregna-4,9(11)-dien-21-carboxylic acid- gamma -lactone (VII), performing esterification on (VII), and then carrying out epoxidation.    USE - The method is useful preparing eplerenone.    ADVANTAGE - The method: utilizes easily available raw materials; adopts semi-synthetic process of microbial fermentation, which is ecofriendly and easy to control; has high product yield, and low cost; and is suitable for large scale production.    DETAILED DESCRIPTION - Preparing eplerenone, comprises (a) taking androstenedione as raw material and introducing hydroxy group at 9th position through microbial fermentation to obtain 9(R)-hydroxy-androstenedione (II), (b) carrying out oxyhydroxide dehydration of 9th position of (II) to obtain 4,9(11)-androst-diene-3, 17-dione (III), (c) etherifying keto group at 3rd position of (III) to obtain 3-ethoxy-3,5,9(11)-androst-trien-17-one (IV), (d) carrying out epoxidation, condensation, and decarboxylation of keto group at 17th position of (IV) to obtain 17 beta -hydroxy-3-oxo-pregna-4,9(11)-dien-21-carboxylic acid- gamma -lactone (V), (e) introducing a double bond between 6 and 7th positions of (V) to obtain 17 beta -hydroxy-3-oxo-pregna-4,6,9(11)-trien-21-carboxylic acid- gamma -lactone (VI), (f) substituting methylfuran at 7th position of (VI) to obtain 7 alpha -(5-methyl-2-furanyl)-17 beta -hydroxy-3-oxo-pregna-4,9(11)-dien-21-carboxylic acid- gamma -lactone (VII), (g) performing oxidation and esterification on methylfuryl group at 7th position of (VII) to obtain methyl (17 beta -hydroxy-3-oxo-pregna-4,9(11)-dien-21-carboxylic acid- gamma -lactone-7 alpha -carboxylate) (VIII), and (h) carrying out epoxidation of double bond between 9 and 11th positions of (VIII).