Abstract: The oscillating effect of the laser beam on the molten pool during laser welding will cause the flow behavior of the molten pool to be different from that of traditional laser welding. Therefore, in order to theoretically explain the characteristics of the molten pool in the oscillating laser welding process, a thermal-fluid numerical model of 5A06 aluminum alloy oscillating laser welding process was built in this paper. The influence of oscillating amplitude and frequency on the heat flow field of circular oscillating laser welding is systematically analyzed. The results show that the increase of the amplitude will reduce the aspect ratio of the molten pool and improve the welding stability. At the same time, the flow behavior of the molten pool is more complex, which increases the material exchange range in the molten pool. The increase of the frequency will inhibit the flow of the molten pool and make it more regular, which is conducive to the discharge of bubbles and reduces porosity.