Phase diagram obtained from small angle light scattering (SALS) and differential scanning calorimetry (DSC) of polypropylene/liquid paraffin blend system indicates that the melts undergo solid-liquid phase separation upon cooling and liquid paraffin is expelled out of crystalline region of polypropylene. Fibers spun under high take-up draw ratio are found to be hard-elastic. Long periods in the meridional direction are observed on the curves of small angle X-ray scattering (SAXS), and the yield point of fibers decreases with the increase in liquid paraffin content, which indicates such fibers have row-nucleated lamellar structure perpendicular to the fiber direction. The feasibility of preparing microporous membranes by stretching such fibers is investigated.