Electron beam welding simulation and joint properties of TC4 titanium alloy and T2 copper were studied. By adopting the welding method of multiple offsets which means welding is carried out on copper first and then on titanium side, and the two welds are close but not connected, the tensile strength of Ti/Cu joints can be greatly improved. In order to explore the thermodynamic behavior of the joints, the finite element method (FEM) was used to analyze the temperature field, deformation and stress distribution, then the strengthening mechanism is discussed in combination with microstructure evolution and mechanical properties. Welding on titanium side can remelt the heterogeneous interface formed by welding on copper side, and improve its stress concentration. The tensile fracture shows that it is brittle cleavage fracture, the phase composition on the fracture surface changes from TiCu to Ti₂Cu, and the brittleness decreases.