Abstract: Ultrasonic welding method was applied to NiTi shape memory alloy with Cu interlayer, and the surface morphology, interface morphology, phase transformation behavior, tensile properties and fracture characteristics of NiTi joint were studied. The results show that ultrasonic welding technique can effectively join NiTi shape memory alloy with Cu interlayer. There are obvious indentations on the surface of NiTi welding due to the effect of sonotrode tip. Well bonding could be observed at the weld interface, and no intermetallic compound was formed. Ultrasonic welding NiTi shape memory alloy showed a reversible phase transition process. The strength of NiTi memory alloy joints reached 65% of the base material, and the fracture surface showed ductile fracture characteristic. Ultrasonic welding method conlat solve the problem of brittle intermetallic compounds produced by traditional fusion welding method, which provides a new solution for the connection of NiTi shape memory alloys.