Abstract: In order to describe the nonproportional cyclic deformation behavior at anisothermal condition,a viscoplastic constitutive model is introduced,which considers nonproportional cyclic additional hardening,the effects of nonproportional cyclic loading history and temperature history.In the model, the evolution equations of back stresses with three different evoluting rates are proposed;a new nonproportionality is defined.To consider the influence of nonproportional cyclic loading history and temperature histor...