Abstract: The influence of different solid solution and aging heat treatment on the microstructure and mechanical properties of TC4 alloy fabricated by electron beam melting were investigated. The results show that the untreated structure is made up of crosswise arranged α-grains with different sizes and orientations, the α-grains and a small amount of β-grains form the net basket structure. After solution and aging heat treatment, the size of α phase increases, when the solution temperature reaches 960 ℃, the microstructure changes from basket microstructure to lamellar microstructure. With the increase of solution temperature, the strength of TC4 alloy increases while the plastic decreases. When the TC4 alloy is treated at the solution temperature of 930℃ and then aging at different temperatures, with the increase of aging temperature, the fine secondary α phase decomposed by martensite α' phase is merged with the surrounding primary α phase, and the microstructure of the TC4 alloy becomes coarse, the strength of the alloy increases first and then decreases while the plastic increases. When the aging temperature reaches 550 ℃, the tensile strength reaches the maximum of 1144.5 MPa, and the elongation reaches 8.7%.