The organic carrier supported metallocene catalyst of the present invention is prepared by preparing a ligand complex of a silicone compound having at least one halogen, an alkyl group and a cycloalkane dienyl group, activating styrene polymer or styrene/divinylbenzene copolymer with a strong base including a metal atom such as Li, Na, K or Mg, reacting the activated polymer or copolymer with the ligand complex of a silicone compound so that the ligand may be supported on the activated polymer or copolymer, and reacting the organic carrier supported ligand with a compound of a transition metal of Group IVb of the Periodic Table or Lanthanides of Atomic Number 58-71. The styrene polymer or styrene/divinylbenzene copolymer may be alkylated by Friedel-Crafts alkylation before they are activated with a strong base.