Abstract: The methanol extract of Huperzia serrata was separated and purified by ODS, AB-8 macroporous adsorption resin, dextran gel Sephadex LH-20 and silica gel column chromatography combined with the semi-pre HPLC. The chemical structures of the isolated compounds were identified by MS, IR, NMR, etc. Four compounds were isolated from Huperzia serrata and identified, named as serratinine C (1), lycobeline C (2), diphaladin A (3) and crenatine (4). Compound 1 is a new alkaloid, compounds 2-4 were isolated for the first time. In vitro biological activity experiments showed that compound 1 could significantly reduce the levels of nitric oxide and reactive oxygen species in glial cells induced by lipopolysaccharide and had significant antioxidant biological activity.