_{Ti-5Al-3V-3Zr-0.7Cr titanium alloy, a new near α titanium alloy, as a candidate material for pressure hull of fusion reactor was researched detailedly in this paper. Firstly, the flow behavior was analyzed by stress-st rain curves obtained by isothermal compression of Ti-5Al-3V-3Zr-0.7Cr alloy, and it was found that the stress decreased with the increasing deformation temperature and the decreasing strain rate, the extent of softeningfirstincreasedthendecreased after 800℃with increasing deformation temperature at higher strain rates of 0.1 and 1s-1, while it decreased continuously with increasing deformation temperature at lower strain rates of 0.001 and 0.01s-1, and the flow stress dropped rapidly after peak stress presenting the dynamic recrystallization characteristics. Secondly, the constitutive model of Ti-5Al-3V-3Zr-0.7Cr alloy was developed in the form of the hyperbolicSsine and the deformation activation energy was calculated to be about 548.74 kJ/mol. Thirdly, Based on the conventional recrystallized fraction curves, the evolution of recrystallized volume fraction is greatly affected by the strain rates and the deformation temperature. The flow softening of the alloy has been proved to be mainly attributed to the occurrence of DRX. Based on the dynamic materials model and Prasad’s instability criterion, the power dissipation map and instability map of Ti-5Al-3V-3Zr-0.7Cr alloy were constructed at strains of 0.4 and 0.6, the obtained optimal processing windows of Ti-5Al-3V-3Zr-0.7Cr alloy were 750℃/ 0.001-0.01s-1 and 850-900℃/ 0.01-0.1s-1 with the peak efficiencies of 65% and 73% respectively.}