Catalyst composition and method of preparing polyolefin using the same

A catalyst composition, comprising;

• a first supported catalyst having one or more organic chromium compounds supported on a support;
• and
• a second supported catalyst having one or more metallocene compounds supported on a support,
• wherein the organic chromium compound includes two or more of a group represented by the following Chemical Formula 1 in a molecule, and has a linkage group (L) linking the two or more groups represented by the following Chemical Formula 1 via 4 to 8 carbon atoms in the linkage group (L):
• wherein * is a part which binds to the linkage group (L) linking the two or more groups,
• R1 to R4 are each independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or an alkoxyaryl group having 7 to 20 carbon atoms;
• Y1, Y2 and Y3 are each independently halogen, hydrogen, a hydrocarbyl group having 1 to 10 carbon atoms, or a heterohydrocarbyl group having 1 to 10 carbon atoms, and
• wherein the linkage group (L) is a group selected from the group consisting of the following Chemical Formulae:
• wherein * is a part which binds to N of Chemical Formula 1,
• R's are each independently hydrogen or alkyl having 1 to 5 carbon atoms, p is an integer of 1 to 6, q is an integer of 1 to 5, and a plurality of R's binding to one ring are the same as or different from each other.