Abstract: In this paper, vibration is applied to stainless steel laser welding. Both parameters of welding speed and vibration frequency are changed respectively in order to find out whether the change of two parameters have influences on joint dimension, microstructure and microhardness. The results show that, all the weld joints are mainly composed with columnar dendrites in the edge of joint and isometric crystal in weld seam centre, and weld structure is austenite and residual δ ferrite. With the increase of weld speed, though both weld width and grain size decrease distinctly while the microhardness of the joint increase, but the growth of columnar dendrites cannot be impeded. The application of vibration can restrains both the size and quantity of the columnar dendrites, and the number of isometric crystal can be increased. So that property of the joint can be improved. The increase of vibration frequency diminish the grain size of the weld zone but the number of equiaxed crystals increase in quantity, and it can be found that fine equiaxed crystals disperse in the boundary of dendrites. The refinement of the grain increase the microhardness of the joint which has an effect of crystal reinforcing. However, vibration frequency has no effect on weld width.