NOVELTY - Preparation of huperzine from Huperzia serrata comprises drying and crushing H. serrata, heating, refluxing and extracting, purifying, and recycling ethanol; concentrating liquid with aqueous hydrochloric acid solution to adjust a pH value of 2-3, extracting using ethyl acetate, removing impurities, and removing organic phase ethyl acetate; purifying the extract with ammonia, adjusting pH value to 9-10, extracting using chloroform, decompressing and distilling; and adding acetone, heating, filtering, and crystallizing.    USE - Method for the extraction of huperzine from Huperzia serrata (claimed) used for promoting learning and memory, and improving memory disorders.    ADVANTAGE - The method produces a high purity huperzine having a white solid purity of 98-99%. The huperzine has no side effect, and is inexpensive.    DETAILED DESCRIPTION - Preparation of huperzine from H. serrata comprises extracting by natural drying and crushing H. serrata, using ethanol water, heating, refluxing and extracting, repeatedly extracting, collecting the extract, purifying the extract by decompressing and concentrating, and recycling ethanol; concentrating liquid with aqueous hydrochloric acid solution to adjust a pH value of 2-3, extracting using ethyl acetate, removing impurities, and removing organic phase ethyl acetate or recycling the acid aqueous phase is for purifying the extracting solution; purifying the extract with ammonia, adjusting pH value to 9-10, extracting with chloroform, combining the chloroform extract, decompressing and distilling to remove chloroform and obtain huperzine total alkaloid; preparing huperzine A crude product using medium pressure liquid chromatography (MPLC) (RP-18), eluting with methanol-water solvent system, eluting with water, removing water-soluble component, using 5-30 vol.% methanol-water, by HPLC detection combining components of huperzine A, concentrating, and vacuum drying to obtain the light yellow solid huperzine A crude product; and adding acetone or ethanol in the crude product, heating to dissolve, filtering, crystallizing at room temperature, and repeatedly re-crystallizing.