Abstract: Ti6Al4V (TC4) alloy is an important material for key structural components in aerospace applications. However, the traditional single-path shielding gas metal inert gas (MIG) welding process suffers from poor arc stability, irregular droplet transfer, insufficient weld protection, and a coarse microstructure, which severely affects the weld formation quality and limits its application in high-end aerospace fields. To address these issues, a coaxial dual-path shielding gas welding process was proposed. The effects of different shielding gas paths on the droplet transfer behavior during MIG welding of TC4 alloy were systematically investigated. Furthermore, the welding process was experimentally analyzed by combining high-speed imaging, electrical signal acquisition, and metallographic observation. The results show that an excessively low single-path shielding gas flow rate easily induces weld porosity defects and causes a coarse microstructure, while an excessively high flow rate triggers the separation and turbulence of the shielding gas flow field, resulting in arc disturbance and heat input fluctuation of the molten pool, which subsequently decreases the microstructure uniformity. When the inner gas flow rate is 20 L/min and the outer gas flow rate is 30 L/min, the droplet transfer is stable, and the arc constriction is uniform. At this time, the fluctuation amplitude of the droplet transfer frequency is smaller than that under the single-gas condition, and no obvious defects are found in the weld; compared with single-path shielding specimens, the martensite microstructure in the weld of coaxial dual-path shielding specimens is significantly refined, resulting in the optimal comprehensive performance of the joint.