Abstract: Electron beam welding was used for the connection of dissimilar metals of TC4 titanium alloy and 1Cr18Ni9Ti stainless steel. The results show that the penetrated crack is formed in the interface of electron beam welding joint without interlayer, which leads to cracking of the joint directly. Taking T2 copper foil as isolation interlayer, electron beam migration is used to control the fusion ratio of metals, which can reduce the production of intermetallic compounds at the TC4/1Cr18Ni9Ti interface, increase the plastic deformation ability of the interface, slow down the stress, and realize the metallurgical combination of titanium alloy and stainless steel. The maximum tensile strength of titanium alloy/stailess steel is up to 256 MPa. The joint without crack and porosity detected by X-ray inspection can be obtained by the electron beam isolation welding.