In order to improve the toughness of polyethylene (PE) necessary for its use as insulation covering of telephone cable for battle field service，an investigation on the blending of PE with poly (eis-1，4-butadiene) (PB) was carried out．This paper presents a study on the influence of the composition of the blends on their supermoleeular structure and properties．Optical microscope，electron microscope，x-ray diffraction and optical depolarization were used for analyzing the supermoleeular structure，while resistance to repeated folding was used as a measure of flexibility of the blends． It is shown that before PB changed from dispersed phase to continuous phase．the higher the content of PB，the better the flexibility of the blends，and that the flexibility of the blends could be increased to 7.6-一11.5 times of that of PE at optimum blending compositions，regardless of whether the PE used was linear，branched or of different molecular weight．