The invention provides an unsaturated polymer hydrogenation catalyst and a preparation method thereof. The unsaturated polymer hydrogenation catalyst is formed by reacting metal organic compounds of IA, IIA and IIIA groups with a nickel/cobalt metal inorganic salt, wherein the metal mol ratio of organic metal to inorganic metal is (1-10): 1. The hydrogenation effect of the catalyst on a homopolymer of conjugated diene or a copolymer of the conjugated diene and vinyl arene is obvious, the hydrogenation selectivity of the catalyst is high and the catalyst is not easily remained in the polymer after a hydrogenation reaction and can be washed by water, so that the catalyst is good for improving the purity and the quality of the polymer.