Catalyst composition and application thereof

A method of preparing an ethylene-based copolymer comprising:

• subjecting ethylene and cycloolefin or enol to a copolymerization reaction using a catalyst composition, wherein the catalyst composition comprises the following components:
• a) a metallocene compound with a structure represented by formula (I) and/or formula (II),
• in formulae (I) and (II),
• Cp1 and Cp2 are each independently C1-C20 hydrocarbyl mono-substituted or poly-substituted cyclopentadienyl or unsubstituted cyclopentadienyl, C1-C20 hydrocarbyl mono-substituted or poly-substituted indenyl or unsubstituted indenyl, C1-C20 hydrocarbyl mono-substituted or poly-substituted fluorenyl or unsubstituted fluorenyl;
• M is titanium, zirconium, or hafnium;
• X1 and X2 are independently halogen atoms, alkoxy, aryloxy, or hydrocarbyl, respectively,
• Q in formula (II) is an atom or a group that connects Cp1 and Cp2,
• b) a co-catalyst component,
• c) a phenol with a structure represented by formula (III),
• each of R1, R2, R3, R4 and R5 in formula (III) is independently a hydrogen atom, a halogen atom, or a hydrocarbyl having 1-30 carbon atoms, and when each of R1, R2, R3, R4 and R5 is independently a hydrocarbyl having 1-30 carbon atoms, any two groups thereof may be closed into a ring.