Abstract: Nonlinear viscoelastic behavior of immiscible polymer blends in largeamplitude oscillatory shear flow (LAOS) is partly due to nonlinearmorphological evolution of its interface. In order to understand theinterfacial evolution of immiscible polymer blends in LAOS, aconstitutive model by Yu and Bousmina^5 is used. Its predictingresults are compared with both the experimental and theoretical resultsof previous studies. As a result, it is found that YB model canreasonably reproduce the experimental results in the evolution of droplength and orientation angle. In addition, a detailed discussion isgiven on the evaluation of nonlinearity of the interface.