A hydrogenation catalyst composition for hydrogenating a polymer of conjugated diene is provided. The polymer of conjugated diene is a homopolymer of conjugated diene or a copolymer of conjugated diene and vinyl aromatics. The hydrogenation catalyst composition includes: (a) a titanium compound, (b) a compound of formula (II), where R5 is C1˜C12 alkyl, alkenyl, amine, ether, ketone or ester groups, R3 and R6 are C1˜C12 alkyl or alkenyl groups, R4 and R7 are C1˜C12 alkyl, alkenyl, amine, ether, ketone or ester groups, n and m are integrals, 1≦n≦3, 1≦m≦3, and (c) alkyl aluminum.