Abstract: The source of welding wire melting heat in the process of hollow tungsten arc welding with coaxial wire feeding is systematically studied by using the method of theoretical modeling and experiment. The results show that the analysis results of the theoretical model based on magnetohydrodynamics are highly consistent with the actual situation. Under the combined action of high temperature arc heat radiation and cathode heat conduction, the gradient temperature zone formed in the inner hole of cathode will preheat the welding wire to a certain extent. The temperature near the geometric center on the central axis of annular hollow tungsten arc is the highest, and the temperature is up to 13 700 K, when the welding current is 400 A. The potential is equal after the droplet contacts with the liquid molten pool. Under the action of the principle of minimum voltage, the anode action area of some high-temperature arc will change from the liquid molten pool to the surface of the welding wire. At the same time, some welding current will flow through the welding wire, and the resistance heat formed is one of the main reasons for the high-efficiency fuse. The results of droplet transfer characteristics analysis show that hollow tungsten arc welding with coaxial filler wire has high process stability and is a new welding method with great development prospect.