Abstract: The super-plasticity diffusion bonding process with phase transformation for TA17 titanium alloy and 0Cr18Ni9Ti stainless steel was investigated. The microstructure, element diffusion and appearance of joint were analysed. The results show that the elements both in Ti alloy and in stainless diffuse on different degree, so forming β-Ti, TiFe and TiFe₂ at the interface. Controlling the thickness of intermetallics compound within 5 μm can improve the strength of the joint. The solid solution based on β-Ti undertakes the main joint strength. The surface area of β-Ti phase affects the strength of joint very greatly. The larger the area is, the higher the joint strength is, vice versa.