The present invention relates to a novel fulvene compound and a preparation method thereof, and more particularly to a fulvene compound having substituted groups in the 2- and 5-positions, prepared from an unsaturated ketone having a substituted group in the .beta.-position and a halogen atom in the .alpha.-position, and a preparation method thereof. The present invention also relates to a metallocene catalyst having a substituted group in the .alpha.-position carbon of the bridge of the cyclopentadienyl group only by reaction of a fulvene compound and an anion group including the cyclopentadienyl group, and a preparation method of a polyolefin copolymer using the same.