The flow stress behavior of Al-Cu-Mg-Ag alloy was tested with Gleeble-1500 machine by isothermal compression at 300～500℃ and strain rate at 0.01～10 s-1

and a constitutive equation model for hot deformation of the alloy was established.The results reveal that the flow stress is increased with decreasing in temperature and increasing in strain rate.The flow stress of the alloy is sharply increased to peak value and then tends towards a constant with raising in strain rate in case of strain rate less than 10 s-1

showing dynamic recovery

while it reaches the peak value and then decreases with the occurrence of saw-tooth fluctuation in case of strain rate of 10s-1 and deformation temperature more than 300 ℃

exhibiting partial dynamic recrystallization.The flow stress of Al-Cu-Mg-Ag alloy during high temperature deformation can be expressed by the Zener-Hollomon parameters in the hyperbolic sine function

and deformed activation energy of the alloy makes 160.08 kJ/mol.