The invention discloses a method for preparing high-purity estra-1, 3, 5 (10)-triene-3, 15 alpha, 16 alpha, 17 beta-tetrol (abbreviated as estratrol), which is characterized in that 3-hydroxy-17 beta-hydroxyestra-1, 3, 5 (10), 15-tetraene is used as a
raw material, and the estratrol is prepared by three steps of phenolic hydroxyl group protection, asymmetric
dihydroxylation and
hydrolysis. According to the preparation method, 3-hydroxy-17beta-hydroxyestra-1, 3, 5 (10), 15-tetraene is taken as a
raw material, 3-hydroxyl is protected by alkoxy-substituted benzoyl, asymmetric dihydroxyl reaction is carried out through
catalytic oxidation of
potassium osmate, double alpha-hydroxyl is introduced to 15, 16-positions, chemical reagents and catalysts with high cost are not needed in the preparation method, and the preparation method is simple and easy to implement. The
dihydroxylation has the advantages of high
stereoselectivity, easiness in purification and separation, mild
reaction conditions and simplicity and convenience in operation, and high-efficiency preparation of high-purity
estetrol (more than or equal to 99.5%) can be realized.