This disclosure relates to a catalyst composition that can prepare polyolefin having high molecular weight, a method for preparing the same, and a method for preparing polyolefin using the same. The dinuclear metallocene compound included in the catalyst composition according to the present invention is a dinuclear metallocene compound with a new structure, and, unlike a single-site catalyst, has high accessibility to a substrate, and thus, can provide a multi-site catalyst with high activity.