Curren t industrial production has put forward higher requirements for welding technology,the optimization of traditional welding methods attracts more and more attention. The external magnetic field acting on the arc plasma will cause a significant change in the arc behavior,which affects the droplet transfer and the forming process of molten pool and ultimately influences the appearance of weld and the quality of welded joint. The research progress of welding behavior under the external magnetic field is mainly introduced,including the effects of external magnetic field on arc morphology,parameter distribution,droplet transfer process,and the formation of molten pool and the appearance of weld. Comparing with the traditional welding,under external magnetic field,the droplet transfer frequency increases,the grain of the weld microstructure is more fine and uniform,and the mechanical properties of welded joint improves.