In this paper, the high temperature deformation behavior and the dynamic recrystallization mechanism of TB18 titanium alloy in 700℃ ~ 900℃ with the strain rate of 0.01 ~ 10 s-1 were studied using the Gleeble 3800 simulator and the electron backscatter diffraction (EBSD) technique. The value of flow stress of the alloy was sensitive to the strain rate and the deformation temperature. In the initial stage of the deformation, the flow stress would soften rapidly after reaching the peak stress, and then it increased to different levels. The Arrhenius-type constitutive equations of the high temperature deformation of TB18 titanium alloy in both α +β dual-phase region and β single-phase region were obtained through data regression. The apparent activation energy in both α +β dual-phase region and β single-phase region were calculated to be 340 kJ/mol and 185 kJ/mol, respectively. The deformation softening mechanism was mainly controlled by dynamic recrystallization of β phase in α+β dual-phase region and dynamic recovery of β phase in β single-phase region. According to the EBSD maps, the metallographic observation and the characteristics of stress-strain curves, it was concluded that the geometric dynamic recrystallization (GDRX) prevailed when the deformation was conducted at high temperature and low strain rate (900°C, 0.01 s-1). As the lower temperature or the higher strain rate was applied, the discontinuous dynamic recrystallization (DDRX) took place at the initial stage of the deformation and the continuous dynamic recrystallization (CDRX) was shown after the strain increased.