Abstract The deformation behavior of Ti-17 titanium alloy was investigated by isothermal compression at the deformation temperatures ranging from 1053K to 1193K, the strain rates ranging from 0.001s−1 to 10.0s−1 and the height reductions ranging from 50% to 60%. The flow stress–strain curve of isothermally compressed Ti-17 titanium alloy exhibits a continuous flow softening feature as the strain rate is higher than 0.1s−1 while it exhibits a steady-state feature as the strain rate is lower than 0.1s−1. The flow stress decreases with the increasing of deformation temperature or with the decreasing of strain rate at a given strain. The critical strain related to peak flow stress increases with the increasing of strain rate in general. The apparent activation energy for deformation at different strains was calculated. The results show that the apparent activation energy for deformation of isothermally compressed Ti-17 titanium alloy decreases from 357.12±89.28kJmol−1 to 192.68±54.46kJmol−1 as the strain increases from 0.1 to 0.8. The processing map of isothermally compressed Ti-17 titanium alloy at a strain of 0.7 was established. The peak efficiency of power dissipation is about 0.54 obtained at a deformation temperature of 1053K and a strain rate of 0.001s−1. The instability region is in the deformation temperature range from 1053K to 1193K and the higher strain rate range from 0.84s−1 to 10.0s−1 at a strain of 0.7.