The invention discloses a method for extracting 
huperzine A from a serrate clubmoss 
herb. The method comprises the following steps: (1) pre-treatment; (2) ultrasonic countercurrent extraction: carrying out ultrasonic countercurrent extraction on the serrate clubmoss 
herb and filtering to obtain leach liquor; (3) membrane separation and purification: centrifuging, and carrying out 
ultrafiltration and 
nanofiltration on the leach liquor to obtain trapped fluid; (4) concentration, namely concentrating the trapped fluid into paste; (5) 
acid dissolution, dissolving the paste by using acid liquid, filtering, and adjusting pH to 
alkalinity; (6) extraction: extracting by using 
chloroform and collecting extract liquor; (7) concentration: concentrating the extract liquor to obtain 
dry powder; (8) 
crystallization and recrystallization: dissolving to obtain the 
dry powder, crystallizing and recrystallizing to obtain white crystals; and (9) 
drying, namely 
drying the white 
crystal to obtain 
a huperzine A product. According to the method disclosed by the invention, the purity of the 
huperzine A extracted from the serrate clubmoss 
herb is greater than or equal to 99%, the product yield is greater than or equal to 0.026%, the final yield is 50-55%, and the yield, yield coefficient and purity of 
huperzine A is high, the extraction time is short, and the cost is low; therefore, the method for extracting huperzine A from a serrate clubmoss herb is suitable for industrial production.