The hot deformation behavior and microstructure evolution of TA15 titanium alloy were systematicallyinvestigated via isothermal hot compression tests conducted at deformation temperatures ranging from 820 to 970 ℃ andstrain rates ranging from 0.001 to 1.000 s-1. The true stress-strain curves exhibit typical flow softening characteristics, withflow stress decreasing with increasing temperature and increasing strain rate. A strain-compensated Arrhenius-typeconstitutive model is established, with a good predictive ability, a correlation coefficient (R) of 0.990 and an averageabsolute relative error (AARE) of 8.26% over the strain rate range of 0.001~1.000 s-1. On the basis of the dynamicmaterials model (DMM), heat-processing maps were constructed, identifying the instability domain at 820~860 ℃/0.1~1.0 s-1, which corresponds to the microstructural features of suppressed recrystallization and abnormally elevated KAMvalues at high strain rates. EBSD analysis reveals that discontinuous dynamic recrystallization (DDRX) dominates at 820 ℃,resulting in the formation of a necklace-like equiaxed fine-grained structure. As the temperature increases to 960~970 ℃,the microstructure evolves into a fully lamellar structure. At temperatures near the β-transus, decreasing the strain rate to0.001~0.010 s-1 favours the formation of a uniform and coarse fully lamellar structure, whereas increasing the strain rate to0.1~1.0 s-1 results in the retention of more equiaxed α phase and refined β grains (from >100 μm to ~15 μm).