Abstract: The thermal deformation behavior of forged and annealed TC4 titanium alloy at a deformation temperature of 800-1 000 ℃ and a strain rate of 0.001~1 s^-1 is investigated by thermal simulation compression test. The constitutive model containing high-temperature compensating factor and the hot working diagram are established. The results show that the deformation peak stress of TC4 titanium alloy decreases with the increasing temperature and decreasing strain rate, and that the increasing temperature contributes to the dynamic recrystallization and softening of TC4 titanium alloy in the cause deformation. The suitable processing temperature and strain rate ranges of the forged and annealed TC4 titanium alloy are 850-980 ℃ and no higher than 0.1 s^-1. The bimodal organization can be obtained near 850~900 ℃ when the strain rate is 0.1 s^-1.