The effects of toolecular weight distribution on the texture formation of as．spun fibe-rs and mechanical properties of polypropylene fibers have been studied．It is shown that the texture formation of as-spun fibers is very sensitive to the presence of high molecalar wei-ght tail in the MWD of polypropylene resin．Under ordinary spinning conditions the as-spun fiber obtained from controHed degraded polypropylene resin showed smectic structu-re with low degree of oritation．However，in the presence of some high molecular weight tail incorproated to the degraded polypropylene resin gave as-spun fibers in a-crystalline modi-fication，although the viscosity average molecular weight and spinning conditions were kept the same．In addition，the birefringence of the as-spun fibers increased sharphy with increa-sing amocnt of the high molecular weight tail in the MWP．The different texture of as-spun fibers resulted in big difference in stretching behavior of the as-spun fiber and mechanical properties of drawn fibers．