The invention discloses a synthetic method of 11 beta,17 alpha-dihydroxy-1,4-diene pregne-3,20-diketone-21-acetate. The invention employs 11 alpha-hydroxy-1,4-diene-16,17-epoxy progesterone (ii) as a starting material, which together with methyl p-toluenesulfonate is subjected to a Mitunobu reaction for inversion under the catalysis of diethyl azodiformate and triphenyl phosphine to obtain 11 beta-p-toluenesulfonyl-16,17 epoxy-1,4-diene progesterone (iii), namely a 11 beta-hydroxy protector; the (iii) is subjected to protective group removal in the presence of HBr, and 16,17-epoxy addition to obtain 11 beta, 17 alpha-dihydroxy-16 beta-bromo-1,4-allyl progesterone (iv); the (iv) is subjected to 3 steps to synthesize 11 beta,17 alpha-dihydroxy-1,4-diene pregne-3,20-diketone (v), which is added with iodine to obtain 11 beta,17 alpha-dihydroxy-1,4-diene pregne-3,20- diketone-21-iodine (vi); and the (vi) is subjected to replacement with potassium acetate to obtain the 11 beta,17 alpha-dihydroxy-1,4-diene pregne-3,20-diketone-21-acetate (i). The method provided by the invention can avoid complex strain breeding, has the advantages of simple operation, high yield, little environmental pollution, and has good industrial application prospect.