The effects of processing parameters on deformation microstructure evolution and dynamic recrystallization behavior of a new near β titanium alloy were investigated by using the Gleeble-3800 thermal and mechanical simulator in the temperature range of 870-970℃ and strain rate range of 10^-3-10s^-1. The results indicate that Ti-7333 alloy exhibits a typical DRX behavior at higher deformation temperature with lower strain rates. The recrystallization grain size and recrystallization volume fraction are also increase with the increase of deformation temperature and the decrease of strain rates. And strain rate affects the recrystallization grain size significantly. The grains are seriously deformed and elongated with higher strain rate (>0.1s^-1) and lower temperature (<870℃), however dynamic recrystallization will hardly occur. The recrystallization grain size is determined by Zener-Hollomon parameter Z, and an exponential function relation is held between D_r and Z. The model of dynamic recrystallization grain size is established by regression analysis method, that is, lnD_r=8.50949-0.31411lnZ. It is able to accurately predict the grain size of dynamic recrystallization under a certain deformation condition and lay a scientific foundation for microstructure controlling during hot deformation. Inappropriate thermal deformation process could cause coarse or non-uniform materials microstructure, thus deteriorating the performance. Thereby, the best hot deformation parameters must be selected from the perspective of microstructure uniformity and grain refinement.