There are mainly the following ways to measure bone density: 1, ultrasound examination method, ultrasound detection advantage is no radiation cost less, but not too accurate. 2, dual-energy X-ray detection method, more formal, more effective, can be divided into qualitative, semi-quantitative and quantitative three categories, which qualitative and semi-quantitative, not as a sensitive indicator of early bone density changes observed, quantitative bone density examination is still the main means of detection. 3, CT examination Measurement, can be for the quantitative detection of bone density, the accuracy is relatively high, but the cost and radiation is large. These are the three most commonly used detection methods in clinical practice. Bone density measurement has important clinical significance in medicine, especially for the diagnosis of osteoporosis, osteochondrosis fibrous osteitis, and diseases affecting calcium and phosphorus metabolism, and the treatment to guide functional exercise.