Abstract: The phase transition point of the Ti80 titanium alloy was determined based on the JMatPro phase diagram calculation. The α+β thermal deformation behavior of Ti80 titanium alloy was studied by thermal simulation compression test, optical microscopy and quantitative analysis method, and the influence of deformation temperature and strain rate on the microstructure was analyzed. The results show that there is a significant difference in the deformation mechanism of Ti80 titanium alloy in the α+β phase region and the β phase region. As the deformation temperature increases, the untransformed α phase gradually decreases. Dynamic recrystallization occurs when the initial α phase is completely transformed into β phase, and the high strain rate leads to incomplete dynamic recrystallization.Deformation temperature and strain rate have significant effects on the characteristic parameters (β-phase grain size, α phase layer thickness and its uniformity) of Ti80 microstructure.