Abstract: 2205 duplex stainless steel (DSS) was welded by autogenous GTAW with arc oscillation. The characteristics of welds section under different excitation currents and its influence on the weld microstructure were studied. The results show that the oscillating arc can promote the penetration of the joint, but the degree of penetration becomes worse with the increase of the excitation current. The oscillating arc can also contribute to austenite precipitation and refine ferrite in the weld of the 2205 DSS joint. The austenite content is the highest when the excitation current is 1A. The increase of austenite content alleviates the increase of hardness value caused by the unbalance of phase proportion and makes the weld hardness closer to the base metal.