Low back pain (LBP) has a high incidence rate and is the leading cause of activity limitation among people under 45 years old. Its causes include abnormal muscle function, ligament injury, and other factors. Traditional imaging examinations have limitations such as radiation exposure, high cost, or static assessment. Musculoskeletal ultrasound, with advantages such as dynamic observation, portability, and no radiation, has gradually become a key technology in diagnosis and treatment. This article systematically reviews the progress in applications of ultrasound technology in the diagnosis and treatment of lumbosacral pain. In terms of etiological diagnosis, ultrasound can assess soft tissues (multifidus muscle, erector spinae muscle function, and fascia lesions such as thoracolumbar fascia), bone structures (lumbar facet joints and sacroiliac joints), and nerve compression (radeiculopathy and nerve abnormalities related to lumbar disc herniation) through multimodal techniqus, providing a basis for etiological identification. Regarding therapeutic applications, ultrasound-guided techniques enable precise localization and are utilized across a range of interventions targeting muscles, ligaments, and fascia (drug injection and acupuncture); joints and spinal structures (intra-articular injection and radiofrequency neurotomy); and nerve roots (drug delivery and ozone therapy). This approach contributes to reduced complication rates and improved clinical outcomes. Ultrasound technology has advantages such as non-invasive dynamic assessment, improved treatment accuracy, simple operation, and low cost. However, it has limitations such as reliance on the operator's experience, insufficient imaging of deep tissues, and the need for more high-quality research verification. In the future, it can be combined with shear wave elastography and shear wave dispersion imaging technologies to assess the elasticity and viscosity of the lumbosacral muscle fascia to improve disease assessment. In conclusion, ultrasound technology provides an important tool for the diagnosis and treatment of lumbosacral pain. With the development of technology and the accumulation of evidence, it is expected to become one of the core diagnostic and therapeutic methods in this field.