Abstract: Objective With the continuous development of finite element technology in the welding field, welding simulation is considered one of the key drivers for the future advancement of welding technology. It can predict physical phenomena during the welding process, joint morphology, thermal deformation, and microstructure, thereby replacing time-consuming and expensive physical tests in the development of new products and processes and accelerating the development cycle. Methods This paper employs a computational fluid dynamics (CFD)-based multiphysics coupling software to simulate the arc under high-pressure magnetically controlled conditions, investigating the relationship between arc morphology and the distribution of the arc temperature field. Results The TIG arc under different conditions was simulated. The simulation results indicate that as the external magnetic field intensity increases, the arc rotation accelerates, the arc length contracts, the temperature distribution of the arc becomes more divergent, the central temperature of the arc decreases, and the radial temperature gradient diminishes. However, within a certain range of magnetic induction intensity, only minor changes are observed in the arc morphology and its temperature field. Conclusion This trend is generally consistent with observations from high-speed imaging, thereby confirming the rationality of the model and the reliability of the simulation. This study provides a theoretical basis and guidance for research on magnetically controlled welding arcs and promotes the widespread application of numerical simulation in magnetically controlled welding.