Abstract: Gas shielded triple-wire indirect arc welding is a novel welding method. In this paper, a stable triple-wire indirect arc system is established. Aiming at solving the problem of sidewall fusion, the influence of arc shape produced by different welding wire distribution on sidewall fusion is analyzed. Aiming at solving the problem of weld seam interlayer fusion, the method of post-tungsten electrode is put forward. The results show that the stable triple-wire indirect arc system can be established by matching the feeding speed with the melting speed of the main wire and the side wire; the arc of wire distribution IV deviates to both sides of the wall along the welding direction and is concentrated form perpendicular to the welding direction, the arc stability is good, the weld sidewall can be fused evenly and the fusion depth is from 1 to 1.2 mm; the weld seam interlayer fusion can be realized by adding the post-tungsten electrode and the tensile strength of the weld can reach 420 MPa.