Huperzine A (huperzine A) is a kind of hemipleurotus alkaloid from Huperzia serrata. It is an efficient, highly selective and reversible acetylcholinesterase (AChE) inhibitor. It is a promising drug for the treatment of Alzheimer's disease (AD). Hup A was higher in stems and leaves than in roots. Huperzia serrata is widely distributed in the world, with 400 different species and genera. In this case, Huperzia serrata grown in Australia, Hawaii and Mainland China is widely used. It was found that the mass fraction of HupA changed little in different seasons. It is also proved that huperzine A has the potential of neuroprotection and prevention of chemical weapons, which has attracted the attention and research of scholars all over the world.