The study investigated the variation of microstructure of a Ti-4.5AL-3Mo-1V alloy during hot compressing in alpha + beta phase field. By scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we systematically examined the influences of hot working parameters on the microstructural features including of the morphology of alpha grain, volume fraction of alpha phase and dynamic recrystallization (DRX). The experimental evidence showed that both alpha and beta phases underwent DRX under the experimental conditions. Moreover, the recrystallization degree of alpha phase was more sufficient than that of beta phase. The DRX was accelerated with increase of deformation temperature and decrease of strain rate. It was also noted that a certain degree of the (alpha -> beta) phase transformation occurred concurrently with the mechanical deformation. In accordance with the microstructural evolution, flow curves of the alloy were characterized by a linear increase until regular oscillations at high strain rates or single peak at low strain rates and softening was followed.