Abstract: Narrow gap welding experiments were carried out on 321 stainless steel for nuclear plants by the novel rotating arc NG-GTAW process. According to the actual welding requirements of 321 stainless steel, the heat input was strictly controlled below 10 kJ/cm, and welded joint with good sidewalls fusion and no obvious defects was obtained. The temperature field and residual stress field distribution of the rotating arc NG-GTAW process were studied, and it was found that during the filling welding process, the highest temperature near the weld reached 600 ℃, at this time, the austenitic stainless steel was in the sensitization temperature range, staying at this temperature for a long time might cause the corrosion resistance of stainless steel to decrease. In the direction perpendicular to the weld, the area near the weld appeared tensile stress, and the stress value was slightly higher than the yield strength of the material. As the distance from the weld increased, the stress value gradually decreased. At a certain location, the tensile stress transformed into a compressive stress. In the direction parallel to the weld, the stress value was higher in the middle area of the plate, and which was lower at both ends.Highlights: The novel rotating arc NG-GTAW process could not only meet the welding heat input requirements, but also improve welding efficiency and reduce the amount of filling, which provided a high-efficiency and high-quality welding method for nuclear-grade stainless steel welding.