A process for preparing a catalyst component made from or containing Mg, Ti, and at least an electron donor compound (ID), including the steps of: (a) reacting a Mg based compound with a Ti compound, having at least a TiCl bond, in an amount such that the Ti/Mg molar ratio is greater than 3 and at a temperature ranging from 0 to 150 C., thereby yielding an intermediate solid catalyst component containing Mg and Ti; and (b) contacting the intermediate solid catalyst component with a gaseous stream containing the electron donor compound (ID) in a gaseous dispersing medium, thereby yielding a final solid catalyst component having an ID/Ti molar ratio ranging from 0.5:1 to 20:1.

The present disclosure provides a method for polymerizing ultra-high molecular weight polyethylene and a method for preparing the catalyst thereof by reacting a main catalyst, a cocatalyst mixed with two or more types of organoaluminum, and an organosilane compound in the polymerization of ultra-high molecular weight polyethylene to have high activity, high bulk density, and high molecular weight while simultaneously having low particle agglomeration.