The dynamic rheological behaviors are measured by small amplitude oscillatory shear on a rotational rheometer for two low-density polyethylene/high-density polyethylene blends: LDPE 2102TN26/HDPE 5306 and LDPE2102TN26/HDPE8916. The composition dependence of zero shear viscosity as well as characteristic relaxation time of the two blends deviate the log addition rule, indicating the two blends are immiscible. Two emulsion models Palierne’s model and Bousmina’s model are used to fit the storage modulus-frequency data, the results indicate the two blends are immiscible except at the 90/10(LDPE/HDPE) weight ratio.