As the final step in the production of nickel-based wrought superalloys, the characteristics of the molten pool in vacuum arc remelting (VAR) have a decisive impact on the cleanliness and metallurgical quality of the ingot. In this study, a multiphysics coupling model integrating electromagnetic effects, fluid flow, heat transfer, and inclusion motion was developed based on the process characteristics of a large-scale vacuum-arc remelted GH4738 superalloy ingot with a diameter of 690 mm. Using this model, the molten pool characteristics, along with the motion trajectories and distribution patterns of inclusions during VAR, were systematically investigated, with particular focus on evaluating the influences of arc current intensity, helium gas cooling pressure, and arc morphology evolution on molten flow and inclusion migration behavior. Results indicate that during remelting, the molten pool primarily exhibits a stable annular flow structure, with inclusion movement exhibiting distinct flow-driven behavior and pronounced size-dependent effects. As the melting current increases from 8 kA to 10 kA, the electromagnetic field strength and thermal input are enhanced, thereby promoting more active inclusion migration within the molten pool. Optimizing the helium cooling pressure to 400 Pa effectively improves molten pool morphology, suppresses turbulence development, and mitigates inclusion entrapment. The arc morphology transition from a diffuse to a constricted configuration fundamentally alters the electromagnetic field distribution, establishing dual circulatory flow patterns that drive inclusion accumulation toward the ingot's central region. Therefore, by rationally regulating the melting current and helium pressure, maintaining a shallow and flat molten pool, and stabilizing the diffuse arc mode, efficient inclusion removal can be achieved as a key processing strategy.