Bone densitometer is the determination of human bone mineral and obtain the relevant data of the medical testing equipment, bone densitometer test results data to T-value-based, but also includes Z-value, bone mineral density, bone volume and other data, bone densitometer to dual-energy X-ray way to test the results of the more accurate, is the International Health Organization (WHO) to adopt the gold standard of bone mineral density, the early 21st century, the mainstream of the market bone densitometer is divided into two categories: dual-energy X-ray bone densitometer and ultrasound bone densitometer. The mainstream bone densitometers in the market at the beginning of 21st century are divided into two categories: dual-energy X-ray bone densitometer and ultrasonic bone densitometer, and there are also single-photon bone densitometers although X-ray bone densitometers but not dual-energy technology. Here mainly introduces the market mainstream two categories of bone densitometer.