Objective To investigate the migration rule of lumbar vertebrae bony structure and the identification method of lumbar spine segment under ultrasound. Methods Ultrasound scanning was performed on 200 patients with low back pain treated in our department, focusing on describing the characteristics of the longitudinal and transverse ultrasound images of the lumbar spine; the migration rule of the bony structures on the longitudinal and transverse lumbar spine, and the the identification method of lumbar spine segment. Results ① Longitudinal section of the lumbar vertebrae bony structure ultrasound acoustic characteristics: it can be roughly divided into 5 sections: spinous process section, lamine section, lamina and inferior articular process section, superior articular process and transverse process root section,transverse process section.When continuously and dynamically sweeping over the lumbar spine, it can be found that the spinous process moves outward to act as a lamina, the lamina moves outward to the upper and lower articular processes and the roots of the transverse process, and the root of the transverse process moves outward to the transverse process. Lumbar vertebrae bony structural features on the cross-section: it can be divided into three sections: the joint section of the upper articular process of the transverse process, the section of the inter-transverse process, andthe section of the lower lamina of the transverse process. ②The determination of the lumbar spine segment can be determined by referring to the 12th rib, spinous process, lamina, transverse process or iliac crest. When the lumbar spine segment is uncertain, a variety of segment determination methods can be used in combination.Conclusion The bony structure of the lumbar spine has a certain migration rule on the transverse and longitudinal planes. Ultrasound is an ideal method for determining the lumbar spine segment.