The invention discloses an active part of Sambucus williamsii Hance with the effect of reducing bone mass loss after menopause. The active part has definite chemical components and mainly comprises seven compounds: vanillic acid, coniferol, levo erythro form guaiacyl glycerol-beta-O-4'-coniferyl alcohol ether, dextro threo form-1-(4-hydroxy-3-methoxyphenyl)-2-[-4-(3-hydroxypropyl)-2-hydroxyphenoxy]-1,3-propanediol, dextro threo form guaiacyl glycerol-beta-O-4'-coniferyl alcohol ether, coniferyl alcohol dehydrogenase and dihydro-coniferyl alcohol dehydrogenase. The active part can remarkably reduce the bone loss of ovariectomized mice, increase bone density of thighbone and shinbone, increase bone volume, does not increase the weight of uterus, and is a component for safely and effectively relieving and improving various symptoms of the bone-related diseases of the menopausal women. The invention has the advantages of providing the active part of the Sambucus williamsii Hance which can be used for preparing a medicament, food or a food additive for preventing and treating the bone-related diseases after menopause.