Isotatic polypropylene (PP) accounts for about 25% of the world plastics made today. PP has a wide range of application. Metallocene catalyst has tended to replace Ziegler-Natta catalyst for PP production because the former has much higher activity and can produce PP with different kinds of microstructures and of a purity that cannot be obtained by the latter. Metallocene/MAO catalysts immobilized on siica can overcome reactor fouling problems and can have a better particle morphology control. Commercially applied porous silica is made by neutralization of aqueous alkali metal silica with acid. The fragmentation of silica particles and the change of polymer morphology during polymerization make it quite difficult to reproduce polymer particle morphologies consistently. Stober method is one of the most important methods for forming monodispersed silica particles. In this study, two monodispersed silica particles with sizes of 5 nm and 700 nm were synthesized via Stober method and were used to support Me2Si(Ind)2ZrCl2)/MAO for studying the effects of silica size and MAO concentration on propylene polymerization activity �, polypropylene particle shape / size and polymer properties. 5nm catalyst exhibited significantly better polymerization activity and produced much more uniform polymer particles than 700nm catalyst did, which were ascribed to their difference of active site amount per particle and their local temperature. With the increase of external MAO concentration, polymer yield �, particle size �, molecular weight and melting point increased but molecular weight distribution decreased. Uniform rod-shaped PP particles were fabricated at an intermediate MAO concentration, which packed with numerous polymer nanofibrils and had a smooth exterior surface.