The morphology and structures of Solvay type β-TiCl3 and δ-TiCls were investiga-ted directly by electron microscope．From electron microscopy it is revealed that in the process of catalyst preparation the products of first and second reaction steps (TiCl3 (I) and TiCl3 (II)) are aggregates of needle-shaped crystallites which were shown to be β-TiCl3 from electron diffraction pattern Similarly，pro-ducts of third reaction step (TiCl3 (III)) are shown to be aggregates of microerystal-lites with a size of～100A and in the form of d．TiCl3．The single crystal of δ-TiCl3 with rough edges was observed for the first time．Therefore．it is ascertained that transformatiou from β-TiCl3 to δ-TiCl3 took place in the third step．Moreover the number of active center on the lateral faces of microerystallites per grain of δ-TiCl3 was caleulated and estimated to be 5×1020 It is very interesting that under tile impingement of electron beam both transformation from β-TiCl3 to δ-TiCl3 and growth of δ-TiCl3 inierocrystallites were observed．Furthermore．it is proposed that during polymerization polypropylene chains would form around every δ-TiCl3 microerystallite and therefore δ-TiCl3 microcrystallites would nlove apart fronl each other，thus they were actually observed as finely dispersed phase in the polymer mass．