Low bone density generally includes bone loss and osteoporosis. For bone loss, if secondary factors are excluded, bone loss can be treated by lifestyle adjustments and supplementation with bone health foundation supplements. The adjusted lifestyle is described as follows: 1, to have a balanced diet, high in calcium and low in salt, protein supplementation needs to be 0.8-1.0g/kg-d, and more than 300ml of milk per day; 2, to have adequate sunlight, sunlight hours are 11:00-15:00, sunlight parts are exposed for limbs and face, sunlight duration is generally 15-30 minutes, sunlight frequency is at least 2 times per week, note For patients with primary osteoporosis, it is important to take calcium tablets and vitamin D in addition to calcium tablets and vitamin D. On top of that, anti-osteoporosis drugs, including bisphosphonates, alendronate, risedronate and zoledronate, as well as teriparatide, raloxifene and osteoporotic triol, are to be used for treatment. For patients with secondary osteoporosis, active anti-osteoporosis treatment is combined with active treatment of the primary disease. Bone density is commonly measured by dual-energy X-ray absorptiometry, i.e. DEXA, quantitative CT, QCT and ultrasound, of which the results of dual-energy X-ray absorptiometry are the gold standard for the diagnosis of osteoporosis, which can clarify whether the patient is suffering from osteoporosis and then determine the precise treatment plan.