The hot deformation behavior and microstructure evolution of metastable β-T51Z alloy during hot compression deformation was sdudied through EBSD and TEM by thermal simulation compression at Gleeble-3500 thermal-mechanical simulator under different deformed temperatures and strain rates.The results show that the compressing curves in hot deformation have a typical characteristic of single-peak dynamic recrystallization,and the degrees of increased stress increase gradually with decrease of deformed temperatures or increase of strain rates. Based on the peak stress,the constitutive equation of thermal deformation of alloy is established, and the activation energy Q is 159.57 kJ/mol,the deformed mechanism of alloy during hot compression is mainly related to the cross slip of dislocation.The deformed temperature and strain rate have a great influence on the deformation microstructure.Dynamic recovery exists throughout hot deformation process,with increase of deformed temperatures or decrease of strain rates, the fractions of dynamic recrystallization increase gradually. When deformed temperature is 800°C and strain rate is 10 s-1,the adiabatic shear band is easily formed and the macro/micro deformation is not uniform.