In this paper, the effects of deformation temperature and strain rate on flow stress of Ti-555 titanium alloy during hot deformation are studied by hot compression tests at high temperature. The constitutive equation of Ti-555 is derived by Arrhenius hyperbolic sine function model, and the processing map of Ti-555 alloy at= 0.6 is established according to the dynamic material model. The results show that the flow stress of Ti-555 alloy is sensitive to strain rate and deformation temperature. The flow stress decreases with the increase of deformation temperature or the decrease of strain rate during hot deformation According to the processing map, the parameters of two hot working safety zones are determined as follows: (1) deformation temperature is 850 ~ 950 ℃, strain rate is 0.6 ~ 10s_^-1; (2) deformation temperature is 950 ~ 1150 ℃ and strain rate is 0.36 ~ 0.9s_^-1.