The electron beam (EB) welding process of Ti casting plates was investigated. For achieving the welds with an acceptable quality, the cross-sectional shape, the microstructure and the tensile properties of the electron beam joint of casting TC4 (ZTC4) alloy were studied. The results show that the double-side molding in electron beam welding of ZTC4 can be achieved by adjusting the welding speed and welding current, but it is difficult to achieve double-sided weld shape in welding the thick plates, and its internal quality meets the standard requirement. The microstructure of electron beam weldment of casting TC4 alloy in the base metal is composed of α laths and β phase, the weld consists of acicular martensites, and the heat affected zone (HAZ) consists of thin acicular martensites, α laths and β phase. The tensile strength of ZTC4 EB-joints is higher than that of the base metal, so the tensile strength of ZTC4 EB-weld can be improved by optimizing the composition and the microstructure of base metal. Impact test shows that stress concentration factor has a great effect on absorbed energy.