Abstract: Objective Traditional welding techniques such as submerged arc welding and CO₂ gas shielded welding face challenges such as low production efficiency and deformation caused by welding stress, making it difficult to meet the advancing demands of low carbon steel welding technology. Efficient and high-quality welding technology that can complete both root pass and cap pass in one welding operation for medium-thick plates has been a crucial research direction in high-end manufacturing fields. Methods The KTIG-MIG hybrid welding method is proposed. A comprehensive KTIG-MIG hybrid welding gun is independently designed, and a hybrid welding test system is set up. Weld build-up on Q235 low carbon steel plates is studied to analyze the effects of wire electrode spacing on the hybrid arc coupling, as well as the influences of KTIG arc current, MIG arc voltage, wire electrode spacing and welding speed on weld form. Results The research results indicate that under a wire electrode spacing of 11 mm, a clear plasma channel forms between the two arcs with good arc coupling and beautiful weld form. Under a wire electrode spacing of 15 mm, the arcs do not couple. Under a wire electrode spacing of 7 mm, repulsion occurs between the two arcs, resulting in unclear arc coupling. KTIG arc current, MIG arc voltage and welding speed exhibit approximately linear relationships with penetration depth. Increasing KTIG arc current promotes deeper penetration depth but has less effect on reinforcement. Higher MIG arc voltage is beneficial for increasing penetration width and penetration depth. With the increase of welding speed, the penetration depth, penetration width and reinforcement will decrease. Conclusion The independently designed KTIG-MIG welding gun effectively completes the welding process, validating the feasibility of the new hybrid welding technology. This lays a foundation for further research and application of hybrid welding techniques.