Abstract: Based on the high-speed photography test,the rotating transfer of the high efficient MAG welding was studied.The movement of the liquid metal jet (LMJ) and the arc were observed during the rotating transfer.The forces acting on the LMJ and the arc were analyzed during the rotating transfer process.The dynamic characteristics of the LMJ and its relation-ship with the motion of the arc were demonstrated.It is the force acting on the LMJ that make the LMJ rotate,then make the arc rotate.Anode spot forces acting on the LMJ can promote the ro-tation of the LMJ,but the viscousness of the cathode spot blocks the rotation of the arc.So a better-controlled process of rotating transfer can be obtained by controlling the special behavior of the MAG arc.