Abstract The triple-arc (Tri-Arc) twin wire gas metal arc welding (GMAW) is an innovative approach to twin-wire welding. It establishes two arcs between the welding wires and the workpiece and introduces a third arc, called the “M arc” between the two wires. To theoretically analyze how various welding parameters affect this process, an equivalent circuit method is employed to establish a dynamic mathematical model for Tri-Arc twin wire gas metal arc welding. The welding process is characterized and simulated using MATLAB simulations to analyze variations in current signals and the wire stick-out. The results indicate that the main arc burns in a dynamic equilibrium state with periodic fluctuations, the current gradually decreases over time, and the arc is elongated. These simulation outcomes closely mirror real welding processes.