The present study describes a rapid and sensitive HPLC method for the quantification of huperzine A (HupA) in Huperzia crispata (Huperziaceae). The sample extraction and preparation involved a simple, time-saving, single-solvent extraction, with each sample being analyzed within 12 min. The mobile phase was ammonium acetate (0.1 M,pH 6.0)-methanol (64 + 36, v/v) at a flow rate of 1.0 mL/min. Detection was at 308 nm. The calibration curve was linear from 0.049 to 7.84 mg(R2 = 0.9997), with intraday and interday precisionRSD of less than 2%. The extraction recovery rate was over 98.49%. Quantification of HupA was performed using this modified method, and the content of HupA was 1.86 times higher in the whole plant of Huperzia crispate (218.17 ± 1.55 mg/g) than in that of Huperzia serrata (117.03 ± 2.97 mg/g). In the whole plant of Huperzia crispata, HupA mainly accumulated in the actively growing shoot tips, the apical bud, and the 10 youngest leaves, reaching 455.23 ± 2.97 mg/g. The content of HupA in the samples from sunshine-sheltered sites was 3.45 times higher than in that from sunshine-abundant sites. The satisfactory results indicate that this modified

method can be applied in the quality control of large-scale Huperziaceae plant extracts and that changes should be made in the cultivation of Huperzia crispata so as to maximize the production of HupA.