The invention discloses a preparation method of rosuvastatin, comprising the following steps of: using 4-fluoropropiophenone as a raw material, followed by a condensation reaction with ethyl isobutyrate to obtain 1-(4-fluorophenyl)-2,4-dimethylpentane-1,3-dione, performing a cyclization reaction with 1-methylguanidine to obtain 4-(4-fluorophenyl)-6-isopropyl-N,5-dimethyl pyrimidine-2-amine, followed by mesyl substituent and bromination to obtain N-(5-(bromomethyl)-4-(4-fluorophenyl)-6-isopropyl pyrimidine-2-yl)-N-methyl methanesulfonamide, and reacting with triphenyl phosphine to form a wittig reagent so as to prepare rosuvastatin provided by the invention. By the adoption of the preparation method provided by the invention, reaction steps are shortened from nine step reactions in original technology to fine step reactions; in addition, two oxidation reactions and an ultralow temperature reduction reaction are avoided, the production efficiency is effectively increased, the product quality is raised, the environmental pollution is minimized, and the production cost is reduced.