Abstract: In order to explore the forming temperature and convective distribution law of the gas metal arc welding (GMAW) short circuiting transfer pool formed by rotary arc surfacing, a three-dimensional mathematical model was established by using Flow-3D software, and a spherical rotaing heat source model was used to simulate the molten pool forming law during the short-circuit transition of the rotating arc in GMAW with workpiece material Q235, considering the gravity, drag force, surface tension and buoyancy. The volume of fluid (VOF) method is used to trace the droplet transition and the free deformation of the pool surface, and the changes of temperature field and flow field inside the molten pool when the droplet enters the pool was analyzed. The results show that during the formation of the molten pool, the rotating droplet has a stirring effect on the molten pool, and makes the liquid metal in the molten pool more active, the flow rate faster, the volume of the liquid metal in the molten pool becomes larger, and the width of the molten pool becomes larger. The simulated weld size and shape are in good agreement with the test, which provide a reference for optimizing the welding process parameters to improve the quality of the rotaryarc GMAW surfacing weld.