The effect of laser welding process on the weld formation and mechanical property of GH188 alloy weld joint is studied. The results show that a high laser power or a low welding speed is disadvantageous for the weld formation of GH188 alloy, there exists the phenomenons of spatter and slight undercut on the weld back, and the grain in weld zone of joint is coarse and the tensile strength of joint is low. With the increase of welding speed, the weld width and the spatter on the weld back both decrease. With the increase of laser power, the weld width and the spatter on the weld back both increase. When the laser power is in the range 2.8-3.2 kW and the welding speed is 6 m/min, the weld formation and tensile property of weld joint are both good.