Propylene polymerization was carried out with MCM-41 supported rac-Et( Ind) 2ZrCl2 catalysts, in the presence and absence of beta-cyclodextrin. The resultant PP was studied by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Through comparison of the results, it was found that the channels of MCM-41 could act as a nanoreactor of propylene polymerization and the polypropylene (PP) contained in the channels had noncrystal structure. However, the PP could grow out of the channels and form some crystals after the active sites on the surface of MCM-41 were destroyed. This showed that the channels of MCM-41 had great confinement effects on propylene polymerization.