Microporous polypropylene hollow fibers were prepared by stretching polypropylene microtubes containing poly (methylsilsesquioxane) fillers with uniform particle sizes. The properties of the resultant hollow fibers are controllable by adjusting the particle size of the filler, the filler content, and the stretching degree. Also, it is elucidated that the hollow fibers have a fine texture of split PP fibrils, in which the filler particles are dispersed.