The influence of strain rate of Microstructures, tensile properties and strain hardening behavior of the electron beam welded joint for TC18 titanium alloy under optimized welding parameters were investigated with three slices (top, middle and bottom). The results showed that the welding led to significant microstructural changes across the joint. The microstructure of fusion zone is composed of coarsened β phase and secondary α-phase. Compared with the base metal, the joint slices along the thickness exhibited a lower strength and plasticity but a further higher hardening capacity. The strength and ductility of the bottom slices are higher than those of the middle and top slices. The maximum yield strength and ultimate tensile strength of the welding slices reached the base metal 83% at the strain rate of 1×10_-2 s_-1. The hardening capacity of welding slices decreased with increasing strain rate. It was significantly enhanced at the middle and bottom slices than the top slice. Tensile fracture occurred in the weld zone.The fracture process of the top slice is cleavage fracture. However, the middle and bottom slices are quasi-cleavage crack.