Abstract: The performances of CCD camera and CMOS camera, which were used in monitoring the laser welding process, were compared.The problems and their solutions in visaul sensing for laser welding process and the common used light path to abstract the imaging signal were introduced.The characteristics of the coaxial and side visual sensing technologies and their state-of-the-arts of developments were summaried.The analyzed results showed that, the active visual sensing technology of Japan is much more advanced than that of the other countries, and the passive coaxial visual sensing technology of Germany is in the leading level in the world, and the laser welding heads with coaxial visual sensor and sending sy stem were developed by some institute and company in Germany.The studies on the visual sensing technologies for laser welding starts relatively late, which has a vast gap with the developed coountries.At present, the visual sensing and monitoring technology for laser welding is mainly used in basic research such as study of the laser welding mechanism, and its application in production is the developing direction of the research and development of coaxial sensing technology.