Abstract: The isothermal constant strain rate hot tensile deformation was conducted on TC4-DT titanium alloy in α+β two-phase region (925 ℃), near-β two-phase region (960 ℃) and quasi-β single-phase region (995 ℃), respectively. And then solution at 950, 940, 960, 980 ℃ and aging at 550, 720 ℃ were carried out. The change trend of flow stress and microstructure after different treatment processes were studied. The results show that in the initial stage of tensile deformation, the flow stress increased rapidly to the peak value and then decreased slowly. The reduction extent of flow stress decreased with the increase of deformation temperature. The higher the tensile deformation temperature or the larger the deformation amount, the less the amount of primary α phase in the microstructure, and the more the needle-like α phase and the lamellar structure. The higher the solution temperature was, the more the needle-like α phase precipitated, and the easier the lamellar structure formed after tensile deformation of at 960, 995 ℃ and solution treatment at different temperatures. The microstructure after hot tensile deformation, solution and aging treatment had little difference from that before aging treatment, but the secondary α phase precipitated on β phases between needle-like α phases; the higher the aging temperature, the coarser the needle-like α phase, and the more obvious the lamellar structure.