Metallocene-catalyzed polyethylene (mPE)/metallocene-catalyzed ethylene-propylene copolymer (mEP) blends were prepared with a mixing apparatus. The morphology of the blends was observed by scanning electron microscopy and the dynamic mechanical behavior of the blends was systematically investigated. Mean-field theories developed by Kerner were applied to these binary blends of different compositions. The Kerner's model calculations were compared with the experimental dynamic mechanical properties of the blends and their morphological characterizations. The results showed that Kerner's model can reasonably predict the viscoelasticity of mPE/mEP blends with different compositions. In addition, the morphological structure of the blends can be estimated via comparing the predicted dynamic mechanical behavior with the experimental data.