Osteoporosis is divided into three categories: primary, secondary and idiopathic, and can occur at different ages and in different genders, mostly in postmenopausal women and elderly men, with serious consequences such as easy fracture of the hip and wrist, increasing the disability and mortality rates. The best quantitative diagnosis is currently based on bone mineral density (BMD) measurement, i.e., dual-energy X-ray absorptiometry, which is commonly expressed as a T value, with T ≤ -2.5 being osteoporosis, -2.5 < t < -1 being bone loss, and t > -1 being normal bone loss. Clinically, many patients are found to have osteoporosis only after fracture. Prevention of osteoporosis should start as early as possible, with regular medical checkups at hospitals for early detection and treatment. In daily life, quit smoking and limit alcohol, drink less strong tea and coffee, get more sunlight, climb stairs and hike appropriately, increase the intake of dairy products and milk products, and take calcium and vitamin D supplements and medication when necessary.