Abstract: Direct diffusion bonding and nickel nano-particles layer diffusion bonding of titanium alloy- stainless steel were investigated by diffusion welding at certain temperature and pressure, diffusion welding under pulsatile pressure and phase transformation super-plastic diffusion welding. Result gained by rigidity testing, rupture observation and micro-structure analysis showed that the strength of bonding gained by diffusion welding at certain temperature and pressure is lower, while the joint obtained by diffusion welding under pulsatile pressure is higher. The degree of diffusion in direct welding affected the strength of the bonding greatly. Better joint was gained by diffusion welding with nickel nano-particles layer, with its strength up to 213MPa, but the density of the nickel nano-particles layer is not high enough, which limited the strength of the joint.