Abstract: The butt welding of 0.2 mm thick TiNi shape memory alloy(SMA) sheet was carried out by using low power impulse laser,and the tensile strength,fracture strain,phase change process and shape memory effect of welded joint were studied.The results show that using low power impulse laser can realize good butt welding of TiNi SMA sheet.The tensile strength of welded joint of cold rolled TiNi SMA achieves 97% of base metal,and fracture strain achieves 95% of base metal.When the welded joint is annealed after welding,its tensile strength is somewhat increased and higher than cold rolled TiNi SMA base metal.The tensile strength of welded joint with post weld annealing treatment achieves 63.6% of annealed TiNi SMA base metal,and fracture strain achieves 82.5%.The phase change process of welded joint with post weld annealing treatment is almost the same with annealed base metal.When the welded joint of cold rolled TiNi SMA is annealed after welding,its phase change process is close to annealed base metal,and its shape memory effect is almost the same with annealed base metal.