A method for hydrogenation of a conjugated diene polymer is provided. The conjugated diene polymer in an inert organic solvent is brought into contact with hydrogen in the presence of a hydrogenation catalyst composition to selectively hydrogenate the unsaturated double bonds in the conjugated diene units of the conjugated diene polymer. The hydrogenation catalyst composition includes: (a) a titanium compound; (b) a compound represented by formula (II) or formula (III): wherein R is C1-C12 alkyl, C3-C12 cycloalkyl, aryl or alkyl aryl, M is C1-C12 alkyl, C1-C12 alkoxy, aryl, alkyl aryl, phenoxy or hydroxyl, and n=1˜3; and (c) a alkylaluminum compound.