The hot deformation behaviors of β-CEZ alloy in the temperature range of 800~1000℃ and strain rate range of 0.001~10s-1 have been studied by hot compressing testing on a Gleeble-3800 simulator at the deformation degree of 0.7. The high temperature deformation behavior, the flow instability and the deformation mechanism in α β phase field and β phase field were studied by the true stress-true strain curves and processing map, which were established based on experimental data and Prasad criterion. The results shows that under the experimental conditions, β-CEZ titanium alloy shows two kinds of softening mechanism: dynamic recovery and recrystallization. The flow stress decreases continuously in α β phase field after the peak stress, decreases slightly and then tends gradually toward a constant value β phase field. The domains with high value of the efficiency of power dissipation (η) at α β phase field is 850~890℃/0.01~0.05s-1, which is the spheroidization of α lamellae area. And the domains with high value of the efficiency of power dissipation (η) at β phase field is 940~980℃/0.2~0.6s-1, which is the dynamic recrystallization area. The domains of flow instability are 800~850℃/0.1~10s-1, 850~900℃/0.1~5s-1 and 900~1000℃/1~10s-1. The manifestations of the flow instability at the α β phase field is the adiabatic shaer band, at the β phase field is the non-uniform deformation.