Welding is an significant link in industrial production, and it is known as the "industrial tailor". However, welding fume, arc light, and metal spatter cause a harsh welding working environment, and the quality of welding has a decisive influence on product quality. Low production capacity, difficult recruitment, and low profits have become drawbacks for the development of the welding field. Combining traditional welding with robots can solve these drawbacks and increase the precision of welding. Welding robots are industrial robots engaged in welding and are mostly used in large-scale manufacturing fields such as automobile manufacturing. Welding robots are divided into spot welding robots, arc welding robots and laser welding robots. In addition, body accuracy and control accuracy are the two main factors that affect the robot welding accuracy. In this case, the sensing technology of welding robot is also essential.