Supported metallocene catalyst component and preparation method thereof and use

The invention discloses a loading metallocene catalyst composition which is obtained through adopting an alkyl aluminoxane/magnesium chloride/silica gel carrier as a carrier and loading a metallocene catalyst precursor, and a preparation method thereof. The catalyst system consisting of the catalyst composition catalyzes ethylene to polymerize or copolymerize and has high polymerization activity. Compared with a common loading metallocene catalyst with an alkyl aluminoxane/silica gel carrier, the activity can be doubled or more. The carrier is simple to prepare; the prepared loading catalyst granule has good shape and adjustable size; and the obtained polythene powdery material has high stacking density.