NOVELTY - Synthesizing 16-epiestriol, comprises e.g. (i) reacting estriol with tert-butyldimethylchlorosilane to obtain 16 alpha -(tert-butyldimethylsilyloxy)-estra-2,4,1(10)-trien-3,17 beta -diol (II), (ii) carrying out acetylation of (II) with acetic anhydride, and reacting with mixed solution of tetrahydrofuran-glacial acetic acid-water to obtain 16 alpha -hydroxy-3,17 beta -diacetyloxy-estra-2,4,1(10)-triene (IV), (iv) reacting (IV) with pyridinium dichromate, and (v) adding obtained compound into mixed solution of potassium hydroxide, water and ethanol, and reacting with potassium borohydride.    USE - The method is useful for synthesizing 16-epiestriol.    ADVANTAGE - The method has simple preparation process and mild reaction conditions; can achieve less discharge of three-wastes; is economical and environmentally friendly; and has high yield.    DETAILED DESCRIPTION - Synthesizing 16-epiestriol, comprises (i) taking dry N,N-dimethylformamide, and imidazole, which is used as acid-binding agent, reacting estriol (I) and tert-butyldimethylchlorosilane for 2 hours to obtain 16 alpha -(tert-butyldimethylsilyloxy)-estra-2,4,1(10)-trien-3,17 beta -diol (II), where the reaction temperature is -40 to -20 degrees C, the molar ratio between imidazole and (I) is 2.4-2.5:1, the molar ratio between tert-butyl-dimethylchlorosilane and (I) is 2.2-2.3:1, (ii) carrying out acetylation reaction of (II) with acetic anhydride and pyridine to obtain 16 alpha -(tert-butyldimethylsilyloxy)-3,17 beta -diacetyloxy-estra-2,4,1(10)-triene (III), where the reaction temperature is 10-25 degrees C, the molar ratio between (II), acetic anhydride and pyridine is 1:8-10:12-20, (iii) adding (III) into mixed solution of tetrahydrofuran-glacial acetic acid-water, stirring and reacting to obtain 16 alpha -hydroxy-3,17 beta -diacetyloxy-estra-2,4,1(10)-triene (IV), where volume ratio between tetrahydrofuran, glacial acetic acid and water in the mixed solution is 1:3-3.5:1-1.5, the reaction temperature is 10-25 degrees C, and the reaction time is 16-24 hours, (iv) adding (IV) into pyridinium dichromate (PDC), glacial acetic acid, and molecular sieve and reacting under catalytic conditions to obtain 3,17 beta -diacetyloxy-estra-2,4,1(10)-trien-16-one (V), where the reaction temperature is 10-25 degrees C, and the reaction time is 2 hours, molar ratio between pyridinium dichromate and (IV) is 1.2-1.3:1, and mass ratio between the molecular sieve and (IV) is 1.5-2.4:1, and (v) adding (V) into mixed solution of potassium hydroxide, water and ethanol, then adding potassium borohydride and reacting to obtain final product, where the reaction temperature is 10-25 degrees C, the reaction time is 2 hours, the concentration of the potassium hydroxide aqueous solution is 0.5-1.5 mol/l, and molar ratio between potassium borohydride and (V) is 1.5-2:1.