The arc welding with weaving has been used widely to obtain better weld quality by avoiding lack of side wall fusion and improve the weld e ciency by obtaining the wide weld bead. But the effect of weaving process parameter change on the weld is not clear. The aim of this work is to study the effect of process parameters on arc behavior and weld formation in Weaving Gas Tungsten Arc Welding(W-GTAW), those parameters include welding currents, tungsten electrode heights from the electrode tip to upper surface of workpiece, weave angles, weave speeds, and weave stop time on the left and right sides. The instantaneous arc shape and electrical signal data were collected by high-speed camera and electrical signal acquisition system respectively. Furthermore, the weld morphology was also systematically analyzed. This result shows that the bottom surface radius of the arc changed with weaving in the W-GTAW. When the weave speed increased to 0.40 × 10 -1 rad/s, the change of the radius was the least, with only 0.10 mm drift, and the difference between the arc forces in the middle and the two sides of the molten pool was smallest. Compared with the stability of each welding process, decreasing the tungsten electrode heights, weave angle and speed could signi cantly enhance the stability of welding. The forming coe cient of weld with a weave angle of 1.9° was 3.11, which might help reduce stress concentration and hot crack tendency of the weld. This shows that increasing reasonable the weave angle and speed can increase the weld penetration from another point of view. Furthermore, the W-GTAW technology shows great application potential in weld forming control by adjusting process parameters.