TiNi shape memory alloy (SMA) and stainless steel (SUS304) were joined by transient liquid phase (TLP) diffusion bonding using Ag-Cu foil as interlayer. The microstructure, the element profile and the phase composition of the joint were analyzed, and the shear strength and the fracture mode of the joint were also investigated. The results show that the interface zone of the joint is composed of TiNi transition zone, middle zone and stainless steel transition zone, and their main phases are Ti(Cu,Ni,Fe), AgCu and TiFe, respectively. The maximum shear strength is about 239 MPa for the specimens joined at 860 °C for 60 min under a specific pressure of 0.05 MPa. The fracture occurs at the diffusion interface between TiNi alloy and AgCu interlayer, and the joint presents a characteristic of ductile-brittle mixed fracture. Based on interface morphology and element diffusion analysis, the kinetics of isothermal solidification was studied. It indicates that the process of TLP diffusion bonding of TiNi SMA and stainless steel shows a typical characteristic of asymmetry.