Abstract: The thermal deformation behavior of in-situ 10vol%（TiC +TiB） reinforced titanium matrix composites was investigated at the temperature of 750-900 ℃ and strain rate of 0.001-1 s^-1on the Gleeble-3800 thermal simulation testing machine by the hot compression deformation test. The microstructure evolution of the composites after deformation was observed using SEM and TEM. The results show that the flow curves of the composites exhibit three stages: work hardening,flow softening and steady-state flow, and the flow stress and peak stress decrease with the increase of deformation temperature and decrease of strain rate. And a constitutive equation of composites based on peak stress under different deformation conditions was constructed, with a correlation coefficient of over 0.96. As the deformation temperature increases,the α phase content gradually decreases, while the β phase content increases. During the dynamic recovery and dynamic recrystallization stages, the dislocation walls are formed, and the temperature increase is beneficial for improving the coordinated deformation of titanium matrix and reinforcing phases, and thereby improving the material properties.