Abstract: Microstructures and properties of TC4 alloy joints welded by electron beam welding were investigated with room-temperature tensile test, room-temperature notch tension test, microhardness test and metallographic analysis. The results showed that the joints with good performance of TC4 alloy may be obtained by means of electron beam welding (EBW). The tensile strength of welded joint is not less than that of the base metal, and the notch sensitive coefficient of the welded joint is less than 1. The hardness of the welded joint and the HAZ are higher than that of the base metal. The microstructure of the weld metal is α' phase (needle martensite) which was transformed from the primary coarse β matrix, and that of the HAZ was the mixture of fine needle martensite and the primary a phase.