Low-power pulsed laser weld the 0.2 mm thickness of TiNi shape memory alloy /stainless steel welding dissimilar materials, the crack of the weld joint morphology and elemental distribution are studied, the reasons for crack formation are analyzed, and crack control measures are proposed. The results show that, TiNi alloy /stainless steel butt welding of dissimilar materials has large crack sensitivity. Only by adjusting the laser welding process parameters can′t avoid cracks. The main reason of cracks is the weld elements Fe, and Ti elements in the stainless steel base metal in the formation of brittle intermetallic compounds, resulting in welds brittle, cracking under sress in the weld. TiNi alloy and stainless steel by pure Ni wire between the pre-filling materials can be diluted as a weld in Fe, Ti element content, on the formation of brittle cracks organizations barrier to avoid cracks. The tensile strength of the welded joint with pure Ni wire as filler material is 580 MPa.