Abstract: To address the challenges in accurately simulating continuous wire feeding and melting during laser wire additive manufacturing under microgravity, as well as the insufficient understanding of melt pool flow and deposit morphology evolution, a three-dimensional transient multiphysics coupling model was developed for this process. The immersed boundary method was introduced to simulate continuous wire feeding, enabling numerical investigation of wire feeding and melting, liquid bridge formation, melt pool evolution, and melt pool solidification. To improve computational efficiency in simulating the complex deposition process, a mesh treatment method based on zonal refinement was proposed. Simulations with different total numbers of mesh cells demonstrated that this strategy significantly improved computational efficiency while maintaining computational accuracy. The simulation results showed that the molten metal primarily flowed from the wire tip toward the rear of the melt pool, where it solidified to form the deposited material. Under the investigated conditions, no significant differences were observed in the melt pool temperature distribution or deposit morphology between microgravity and normal-gravity environments. This study provides an effective numerical approach for simulating laser wire additive manufacturing under microgravity and offers a reference for subsequent process control and theoretical analysis under different operating conditions.