The invention relates to a preparation method of beta-
artemether, which comprises the following steps: adding
methanol and
artemisinin into a container, cooling to-8-5 DEG C, adding a
reducing agent in three batches, stirring and reacting for 1-3 hours to obtain
dihydroartemisinin after the
reducing agent is completely added, controlling the temperature to 0-10 DEG C when the central control is qualified, dropwise adding an etherifying
reagent into the
dihydroartemisinin, stirring for 5 minutes, adding trimethyl orthoacetate, and reacting for 1-3 hours to obtain the beta-
artemether. The central control is qualified, the temperature is controlled to be 0-10 DEG C, drinking water is dropwise added, heat preservation and stirring are carried out for 1 h, filtering is carried out, an
artemether crude wet product is obtained,
drying is carried out, and beta-artemether is obtained. According to the preparation method, the average etherification yield is about 90%, the total etherification yield is about 85%, the crude product purity is about 99.5%, the yield is greatly improved, and the preparation cost is reduced.