To investigate anti-osteoporosis active constituents of Lycopodium fargesii Hert.,the ethanol extracts of L. fargesii were isolated by silica gel,MCI,RP-18,Sephadex LH-20 column chromatography and semi-preparative HPLC methods.Eighteen compounds were obtained from the ethyl acetate fraction.Their structures were elucidated as α-onocerin(1),26-nor-8-oxo-α-onocerin(2),serrat-14-en-3β,21α,24-triol(3),serrat-14-en-3β,21β,24-triol(4),1,20-eicosanediol(5),tricosane(6),glycerolmonolinoleate(7),glyceryl linolentate(8),3-(4′-formylphenoxy)-4-methoxybenzaldehyde(9),apigenin(10),4-hydroxybenzaldehyde(11),vanillic acid(12),3-hydroxy-4-methoxybenzoic acid(13),2-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-propan-1-one(14),3-hydroxy-4-methoxyzimtaldehyde(15),8-acetoxy-5-hydroxyumbelliprenin(16),trans-4-hydroxy-2-nonenoic acid(17) and decane-1-thiol(18) by analysis of their NMR and HR-ESI-MS data as well as by comparison with the literature reported data.Compounds 1-18 were isolated from L. fargesii for the first time.Compound 16 displayed significant anti-osteoclasts activity with IC₅₀ value of 1.98 μM.