Abstract: X2A66 was tested in isothermal compression experiment by using the Gleeble-3500 thermal simulator with the deformation temperature range of 350～470癈 and the strain rate range of 0.001～10s-1. The alloy peak stress constitutive equation and processing map were established by utilizing hyperbolic sine function and dynamic materials model. The results show that flow stress of X2A66 decreases with the increase of deformation temperature and increases with the increase of strain rate. In addition, the strain rate has no effect on temperature sensitivity of X2A66 and high strain rate which is above 0.1s-1. In X2A66 isothermal compression experiment, the relationship between the peak flow stress and strain rate satisfies hyperbolic sine function and the constitutive equation is : =5.09?09[sinh(0.019σ)]4.54414exp(-145.377/RT) In the range of test parameters, the instability zones of X2A66 alloy are mainly concentrated in area of high strain rate. The peak area of dissipation efficiency is the strain rate range of 0.001～10 s-1 and the deformation temperature range of 700-743K, which is the best thermal processing zone for X2A66.