Abstract: As an efficient and precise processing method, laser welding is influenced by factors such as workpiece condition, processing techniques and environmental disturbances, which can lead to poor weld formation or welding defects.Online monitoring and intelligent regulation are core problems for large-scale application of laser welding. Optical coherence tomography(OCT) technology can directly obtain the dimensions, morphology and other characteristics of the processed structure. It has advantages such as non-contact, high resolution, strong anti-interference capabilities and easy system integration, showing great potential in the field of laser welding quality monitoring. The basic principles, system composition and key performance indicators of OCT technology were systematically elaborated. The application of OCT technology in weld seam morphology measurement and real-time detection of small hole depth was introduced. The research progress in the post-processing of measurement data was analyzed, and the development trend of OCT technology in the field of laser welding was discussed. This provides new insights for the intelligent monitoring of the entire laser welding process.