Abstract: A catalyst for the polymerization of propylene comprising components (A), (B) and (C) is provided. Component (A) is a solid product prepared by dissolving a halide of magnesium in a solvent system consisting of an organic epoxy compound, an organic phosphorus compound and an inert diluent to form a homogeneous solution; mixing the homogeneous solution with a halide of titanium to form a mixture; precipitating a solid from the mixture in the presence of an auxiliary precipitant; treating the solid with a polycarboxylic ester to load the ester on the solid; and treating the ester loaded solid with the halide of titanium and the inert diluent. Component (B) is an organic aluminium compound, and component (C) is an organic silicon compound. The particle size of the catalyst can be adjusted by increasing the amount of the inert diluent at a low ratio of the epoxy compound to the phosphorus compound.