Abstract: Surface guided radiation therapy (SGRT) is a non-radiation, non-invasive technology that provides continuous postural monitoring of patients during radiotherapy. Using advanced 3D optical surface localization and tracking technology, SGRT quickly captures the surface contour information of patients through optical means to generate high-precision 3D surface contours, enabling real-time monitoring of patients during radiotherapy to ensure its accuracy. This image-guided technology has been widely applied in radiotherapy for tumors in different parts of the body, such as breast, intracranial, head and neck, and limbs. SGRT can reduce initial setup errors and provide real-time monitoring during treatment, or be combined with respiratory gating and deep inspiration breath-hold techniques. SGRT can also reduce radiation dose by reducing the use of CBCT, improve patient comfort with the use of immobilization devices, and enhance clinical speed, efficiency, and safety. This review aims to provide an overview of the commonly used technology and clinical applications of SGRT, and discuss its current limitations and future prospects.