In this article, preparation of novel MgCl2-adduct supported spherical Ziegler-Natta catalyst for alpha-olefin polymerization is reported. The factors affecting the particle size (PS) and particle size distribution (PSD) of the prepared support were investigated. In this method, the internal donor added while preparing MgCl2-adduct support was supposed to act as a crosslinking agent. Therefore it provided a reasonable way to enhance the morphology and control the PS of the resultant polymer particles. The possible mechanism is discussed. (c) 2005 Wiley Periodicals, Inc.