Abstract: Electric arc is the most common applied welding heat source. The dynamic variation of welding current and arc voltage,the shape,dynamic behavior and characteristic parameters of welding arc were studied and analyzed,which could be used to evaluate the arc stability and control effectively the welding process,and are helpful to improve the intelligence level of welding manufacturing and the quality of weld appearance and welded joint. In this paper,the research and progress in several aspects,made by scholars at home and abroad,were summarized,such as the signal analysis and processing on the welding current and arc voltage to evaluate the stability of welding process,characterize and quantitative analyze the behavior of arc burning and molten droplet transfer based on the visual sensing and image processing,the numerical simulation of welding arc,and so on. It is expected to have a comprehensive and sufficient understanding on the research methods and current situation to the welding arc and its dynamic behavior characteristics,and to promote the further development of research work and widen the application in engineering practice.