Abstract: The structure evolution characteristics of molten pool center and static spheroidization mechanisms of grains at the edge region of SLM-fabricated Ti175 high-temperature titanium alloy during heat treatment were systematically investigated. The results show that due to the cooling rate differences during SLM process, coarse lath α' martensite at the molten pool center and fine acicular α' martensite at the edge form respectively, and the grain orientation distribution at the edge is random due to high dislocation density and residual stress accumulation. After 960 ℃×1h furnace cooling, the grains at the edge region undergo residual stress release-driven static spheroidization via dislocation rearrangement and subgrain boundary evolution, reducing intra-grain misorientation below 3°. The center region experiences Ostwald ripening-dominated lath coarsening while retaining original morphology due to lower dislocation density and residual stress. Spheroidization proceeds through curvature-driven end migration and residual stress-driven subgrain boundary evolution, achieving dynamic equilibrium between the formation of low-energy dislocation structures and interfacial energy minimization. This work elucidates microstructural regulation under residual stress gradient and thermal field, providing theoretical guidance for optimizing SLM titanium components.