Abstract: Experiment of laser spot welding of LF6 aluminum with double laser beams was carried. The cross-section of laser spot welding joints with single laser beam and double laser beams were compared, and the effects of laser power, pulse duration and power ratio on the weld joint dimension were investigated. The experimental results indicate that when the power is fixed, the double laser beams can increase the keyhole diameter and improve the stability of the keyhole, decreasing the number of pores, increasing the dimension of fusion area. It is discovered that the dimension of top sheet's change is small, when the laser power changes. And the area of weld joint in the bottom sheet is smaller than that in the top sheet when the laser power is low. At the same total input power, the crater depth with the laser power ratio 1:1 is much smaller than that of laser power ratio 1.5:1.