Osteoporosis (osteoporosis) is a systemic bone disease characterized by a decrease in bone mass and destruction of the microstructure of bone, manifested by an increased brittleness of the bone and therefore a much higher risk of fracture, even with minor trauma or in the absence of trauma. Osteoporosis is a chronic disease caused by multiple factors. There are usually no specific clinical manifestations until a fracture occurs. The disease is more common in women than men, and is commonly seen in postmenopausal women and the elderly. With the increase of the elderly population in China, the incidence of osteoporosis is on the rise and is a health concern in China and globally. The World Health Organization has ranked osteoporosis as the second most dangerous disease to human health. About 69.44 million people over 50 years old in China suffer from osteoporosis. Therefore, in order to prevent and treat osteoporosis, bone density tests should be done when women are over 45 years old and men are over 50 years old. The full name of BMD is bone mineral density, which is an important indicator of bone strength, expressed in grams per square centimeter, and is an absolute value. In the clinical use of bone density value due to the different absolute values of different bone density testers, usually use the T value to determine whether the bone density is normal. Clinically, bone density is commonly measured by dual-energy X-ray absorptiometry (DXA) and other methods. So, how should the bone density test results be interpreted? Bone density test is expressed by T-value, which is a relative value with a normal reference value between -1 and +1, and is abnormal when it is lower than -2.5. Values can be referred to the following data: T value ≥ -1.0 in normal individuals; low bone mass: -2.5 < T value < -1.0 osteoporosis: T value ≤ -2.5 severe osteoporosis: T value < -2.5 with more than one site of fracture. According to the clinical classification, it can be divided into: primary osteoporosis, secondary osteoporosis, and idiopathic osteoporosis, of which primary is mostly old age, secondary is mostly female post-mortem, and idiopathic is mostly young people combined with other disorders.