Hot compression tests of equal channel angular pressed Mg-4Zn alloy were conducted on a Gleeble-3800 thermal-mechanical simulator at 200～350℃and 0.001～1 s

-1

.The deformation activation energy（Q）was calculated using a hyperbolic sine constitutive equation.The results show that Qis increased with strain increase.At the beginning of deformation

the rate controlling process is characterized by lattice self-diffusion controlled.At the late stage of deformation

the rate controlling mechanism is characterized by the cross-slip of dislocations.Based on the dynamic material model

the processing maps of Mg-4Zn alloy were established.The areas of the instability domains are decreased with increasing in strain since the initiation of non-basal slips and cross-slip enhancing the dynamic recrystallization process.Workability domain occurs at 260～350 ℃ and 0.01～0.1 s

-1

.