Abstract: The samples of TC4 titanium alloy were prepared by TIG arc additive manufacturing, and the samples were normalized. The results show that the microstructure of the sample is composed of α phase and β phase after normalizing treatment. And the acicular primary α phase becomes shorter and thicker with the increase of normalizing temperature at the range of 750 ~ 950 °C, and gradually changes to the direction of net basket structure. At the range of 950 ~ 1 050 °C, some primary α phases develop toward "pseudo-equiaxed crystals", and form structures which comprises the "pseudo-equiaxed crystals" primary α phase + the fine needle-like primary α phase + (α + β) structures between the fine needle-like primary α phases at 1 050 °C. The better mechanical properties of the present work (in conditions of 850 °C/2 h/AC) show that tensile strength, yield strength, elongation and reduction of the area in y direction are 900.4, 820.4 MPa, 9.3%, and 27.4% respectively, and tensile strength, yield strength, elongation and reduction of the area in z direction are 890.1, 790.1 MPa, 10.8%, and 31.0% respectively, which is close to the standard requirements for forgings. The hardness of sedimentary state and normalizing state has little changes. The fracture morphology of tensile specimen (z tensile specimen and y tensile specimen) is full of dimples and belongs to plastic fracture.