Abstract: Clockwise circular oscillation (CW) laser welding experiments are carried out on 8.0 mm thick 5A06 aluminum alloy. Considering the beam oscillating trajectory and energy superposition effect, the energy distribution model of the workpiece surface is established. The effects of beam oscillation frequency and oscillation amplitude on joints’ forming and energy distribution are studied, and the influence mechanism of the interaction between the linear and circular motions of the beam on the energy distribution is revealed. The results show that compared with conventional laser welding, the action range of the oscillating welding beam becomes larger and the melting width increases significantly, which provides greater gap adaptability for butt welding. The surface energy of the workpiece changes from a single peak to a double peak, showing a “high on both sides and low in the middle” distribution, and the energy peak is 1/5 of that of conventional laser welding. When the oscillating frequency is 200 ~ 300 Hz and the oscillating amplitude is 1.5 ~ 2.5 mm, the laser energy distribution is relatively uniform, the undercut and spatter defects are almost eliminated, and the weld is well formed. When the oscillating amplitude increases from 1 mm to 3 mm, the energy superposition effect is weakened, the energy inhomogeneity is enhanced, and the energy peak is reduced. When the oscillating frequency increases from 100 Hz to 200 Hz, the uniformity and symmetry of energy distribution will get improved. When the oscillating frequency increases from 200 Hz to 300 Hz, the local superposition effect will be enhanced and the energy asymmetry will increase.