The invention relates to a composition for increasing the bone mineral density and preparation and a preparation method thereof. The composition is mainly prepared from, by weight of parts, calcium carbonate, D-glucosamine hydrochloride, chondroitin sulfate, collagen protein, a casein phosphopepetides, a davallia mariesii extract and a vitamin K2. On the specific matched condition, the effect of remarkable synergistic interaction for treating osteoporosis is achieved, and the effects of blocking calcium loss and reinforcing calcium absorption are achieved; after traditional Chinese medicines of shaddock peels, chicken shells, purple bergenia herb and schisandra chinensis are added, the effect of increasing the bone density is further enhanced, and meanwhile the effects of treating the joint inflammation, tonifying the spleen and the kidney, strengthening tendons and bones, improving immunity and the like are achieved.