Abstract: In view of the limitations of existing dual-wire welding technology, a new dual-wire single-arc welding method was proposed. This method's welding system consisted of a single power supply, a single wire feeder, and a single welding torch. The dual wires were attracted to each other under the action of electromagnetic force to form a single electric arc and a co-droplet, effectively addressing the arc interference problems commonly encountered in conventional dual-wire welding. The upper limit of usable current for gas-shielded welding was significantly expanded as well. The impact of wire spacing on droplet transfer behavior and weld appearance was analyzed using high-speed imaging and synchronized information equipment, while the optimization of droplet transfer behavior was achieved through adjustments in welding waveform parameters. The results demonstrate that with an applied current of 485 A, as the spacing between the dual wires increases, the droplet transfer mode transitions from single-pulse to double-pulse and eventually to multiple-pulse per droplet. This transition frequency gradually decreases while the stability of the welding process deteriorates. When the wire spacing is adjusted to 2.8 mm, optimizing waveform parameters allows for an increase in welding current up to 598 A. Under these optimized conditions, a bowl-shaped weld cross-section is achieved with a deposition efficiency of approximately 14.1 kg/h. By controlling both wire spacing and current, it becomes possible to partially decouple the forming coefficient, providing a novel approach and perspective for optimizing welding processes.