Abstract: The typical molten pool of high energy beam welding is in nailhead shape with large aspect ratio. In order to simulate it more precisely, a new heat source model, Rotary-Gauss body heat source model, is established. Numerical simulation and experiment are performed to verify it. The results indicate that using the new model can obtain a better result in temperature field computation compared with other heat source models. In addition, the comparison and analysis are helpful to understand the characteristics of different heat source models deeply, so that it will be easier to choose the right heat source model to simulate the high energy beam welding with high efficiency.