Abstract: According to the requirements of a special raw material, through the optimization and improvement of the existing forging process, a large-scale TC4 titanium alloy bar was prepared by the 6-fire forging. The distribution law of microstructure and properties of large size forged billets at different sections after deformation was studied. The results show that the macrostructure at the end of the bar is poor after forging deformation. The microstructure after deformation is dual-phase zone structure with high α phase content. The α phase content from the end to the middle increases and the equiaxed degree is more obvious, while the β transformation structure and grain size gradually decrease from the end to the middle of the bar. At the same section, the β transformation structure from the edge to the center decreases, and the thickness of lamellar α phase increases gradually and tends to be equiaxed. After deformation, the strength at the end of the bar is obviously lower than that of the middle, while the plasticity is bigger and the impact toughness is smaller. At the same section, the strength from edge to center decreases, the plasticity and impact toughness increase gradually.