Abstract： The local dry underwater laser welding was applied on 1mm thick SUS304 stainless steel. The effect of water depth and shielding gas flow rate on the weld forming and weld mechanical property was investigated. The results show that when the water depth and shielding gas flow rate is appropriate, the weld with good shaping can be obtained. Meanwhile, the tensileshear strength of weld is similar with that of base metal. At a given water depth, when the gas flow rate increased, the weld width increased, and when weld penetration decreased, the depth-to-width ratio decreased. When the gas flow rate was constant, the variation of weld width and weld penetration is similar when the water depth increases. Compared with the traditional laser welding, the underwater laser welding changes the direction and rate of heat dissipation, resulting in the lessening of weld penetration and widening of weld width.