Abstract: The high temperature behavior of BT25 titanium alloy was investigated from 950 ℃ to 1 100 ℃ and strain rate range 0.001 s^-1 to 10 s^-1. The effects of thermodynamic parameters on flow stress and microstructure were analyzed. Based on the arrhenius equation, the constitutive equation was constructed and validated. The results show that at the same temperature and strain rate, the larger the deformation, the more the dynamic recrystallization is. At the same deformation degree, the lower the deformation temperature and higher the strain rate, thefiner the dynamic recrystallization grain size is. The flow stress increases with the increase of strain rate, and decreases with the rising deformation temperature. The deformation activation energy of BT25 titanium alloy is 763.51 kJ/mol in α+β phase region(950~1 010 ℃) and 231.36 kJ/mol in β phase region(1 040~1 100 ℃).