The hot compression tests at high temperature of Ti55531 alloy were conducted by Gleeble-3500 thermal simulation test machine, and the flow stress curves with temperatures of 1033-1183 K, strain rate of 0.001-1 s-1 and height reduction of 60% were obtained. The results show that the flow stress increases rapidly and reaches a peak value due to the predomination of workinghardening at the initial stage of deformation and decreases with the increasing  of strain due to the predomination of softening effect. On the basis of Arrhenius constitutive equation, the deformation activation energies of Ti55531 alloy in dual phase region and single phase region are 280.25 and 183.14 kJ·mol-1 respectively by data calculation and fitting. Meanwhile, considering the influence of deformation temperature T on the material parameter A, the relationship between material parameter A and deformation temperature T is developed. Subsequently, on the basis of the obtained Qvalue and Avalue, the Arrhenius constitutive models in single phase region and dual phase region are constructed.