Abstract: A one-dimensional nonlinear constitutive equation for describing both long period viscous effect and short period elastic effect has been presented according to Frechet series given by Green-Rivlin. The parameter vers of constitutive equation were determined by means of curvilinear regression of experimental data in the creep tests for a sort of asphalt mixture.The results indicate that the constitutive equation is valid for the strain response with different histories of stress.