Dissimilar materials of TiNi shape memory alloy (SMA) and stainless steel of 0.2 mm thickness were butt welded by micro impulse laser and the microstructure characteristics of the weld joint were studied. The results show that good joining between TiNi SMA and stainless steel can be realized with pure Ni wire as filler material and micro impulse laser as welding heat source. The microstructures of weld center are fine equiaxed crystals and the main elements in weld seam are Ti, Ni and Fe. In weld seam, the content of Ti is similar to that of stainless steel base metal, while Ni is a little more than that of TiNi SMA base metal and much more than that of stainless steel base metal. There is little Fe element in TiNi SMA base metal. There is an obvious interfacial zone of about 10-20 μm width between TiNi SMA base metal and the weld, and there are Fe and Cr elements in the interfacial zone, which diffuse from stainless steel base metal. The width of the interfacial zone between stainless steel base metal and the weld is small and the interface is a line