Abstract: With rapid social and economic development, high-efficiency welding technology has become an important development direction in the field of welding. In recent years, scholars and professionals in many countries have devoted themselves to further increasing the welding efficiency by improving welding materials, welding process, and arc-welding equipment. The welding efficiency can be increased using two approaches: one is increasing the welding speed, the other is increasing the welding deposition rate. Considering these two methods, typical technologies such as multiwire submerged arc welding (SAW) and multiwire gas metal arc welding (GMAW) were proposed. A twin-arc integrated cold wire hybrid welding system was established. The mechanical effect of the cold wire position on the welding process was studied, including its effects on heating, melting, and weld surface formation. Results show that the melting of cold wire depends on the front end of the weld pool, and the melting effect of the weld pool on the cold wire is not sufficient when the cold wire is fed in front of two leading wires. The end of the cold wire makes contact with the bottom surface of the weld pool with the continuous feeding of the cold wire. Droplets melted at the wire ends are ejected and fall on the base metal surface to generate a globular spatter with the backward motion of the base metal. The thermal distribution on the side of the weld pool decreases as the cold wire is fed inside of the two leading wires. Hence, the flow of molten metal is affected, ultimately leading to an uneven weld formation. The cold wire is stably inserted into the weld pool when fed behind the two leading wires, representing the optimum cold wire position. Moreover, the deposition rates increase with an increase in the cold wire feed speed and show little change under two-pulse phase differences (in-phase and reverse-phase pulse differences). The effect of arc heating and melting on the cold wire was most intense at the in-phase pulse current, followed by the reverse-phase pulse current and subsequently direct current.