Abstract: By using the nonlinear ZWT model and the genetic algorithm method and taking the rate-dependent effects and damage evolution into account, experiments in the quasi-static and impact loading were performed to study the visco-elastic mechanical behaviors of PP/PA polymer blends with two types of interface modifier in the large deformation condition. The nonlinear visco-elastic constitutive equations considering damage evolution for these materials were obtained respectively. Results show that the deformation mechanisms of polymer blends with two different compatibilizers in the large deformation condition are different due to the visco-plastic effect, and that the visco-plastic deformation influences the polymer blend with TPE-g as compatilizer more greatly than the polymer blend with PP-g-MAH as compatilizer, and the strain range, in which the ZWT model can be applicable, is 15% for the former, while for the latter it is 24%.