Preparation method of R-budesonide

The invention discloses a preparation method of an adrenal cortex hormone medicament and particularly relates to a preparation method of a high-purity R-budesonide isomer. According to the method disclosed by the invention, prednisolone is used as an original raw material and the budesonide acetic ester is prepared by cyclization, ring opening, esterification, elimination, oxidation, cyclization and hydrolysis. The method disclosed by the invention has a simple process and high yield and is suitable for industrial production.