The MgCl2/SiO2 complex support was prepared by spray drying using alcoholic suspension, which contained MgCl2 and SiO2. The complex support reacted with TiCl, and di-n-butyl phthalate, giving a catalyst for propylene polymerization. The catalyst was spherical and porous with high specific surface area. TEA was used as a cocatalyst, and four kinds of alkoxysilane were used as external donors. The bulk polymerization of propylene was studied with the catalyst system. The effect of the reaction conditions and external donor on the polymerization were investigated. The results showed that the catalyst had high activity, high stereospecificity, and sensitive hydrogen responsibility. Polypropylene has good grain morphology because of duplicating the morphology of the catalyst. (c) 2005 Wiley Periodicals, Inc.