Pure nickel wire is added into the butt joint of 0.2 mm thick TiNi alloy/stainless steel, and they are welded by pulsed laser. The morphological image and the interface microstructures of the fusion area are investigated. The results show that the characteristics of the welded joint center is extension of the continuous growth grain. The length of the fern-leaf crystal can reach about 200 μm which may span several fish-scales lines formed by pulsed laser. The morphological image of welded joint with both sides of base material fusion is completely different. In the joint interface of stainless steel base material, the branch crystal grows along fusion line of stainless steel base material, and there have second crystal axis between the branch crystals. In the fusion area between TiNi alloy and welded joint, there is a transition layer between TiNi alloy and welded joint, whose width is about 5 μm.