Continuous laser lap welding process test is conducted on 304 stainless steel sheet, and effects of process parameters on weld shape and weld properties are studied. The results show that surface width, back width and lap shear stress of the weld increase with the increasing of laser power and decrease with the increasing of welding speed. On the premise of good weld formation, change of defocusing distance has smaller influence on weld quality. One side welding with back formation is realized when the gap is within 0.6 mm. The microstructure is fine equiaxed crystal in weld center and small columnar crystal in the junction of weld metal and the parent material, and the heat affected zone is not obvious.