The invention discloses a supported 
ruthenium catalyst and a preparation method thereof. The preparation method is characterized in that the preparation method comprises the following steps: 1, preprocessing a carrier with a soluble 
alkaline earth metal salt, wherein the 
mass of the soluble 
alkaline earth metal salt accounts for 0.1-20% of the 
mass of the carrier; and 2, dipping the 
alkaline earth metal salt processed carrier with a material which comprises a primary 
active component metallic 
ruthenium and an assisted catalytic component comprising one or several of Ni, Co, Pd and Pt, wherein the 
mass of the 
primary component metallic 
ruthenium accounts for 0.1-5% of the carrier, and the mass of the 
secondary component comprising one or several of Ni, Co, Pd and Pt accounts for 0.01-5% of the mass of the carrier. The catalyst of the invention is mainly applied to the selective 
hydrogenation process of an aromatic ring of an aromatic compound, wherein the aromatic ring of the aromatic compound has at least one 
alkyl group, one ester group, one hydroxyl group or an amino group and also has at least one C1-8 
alkyl group. Compared with catalysts prepared with the prior art, the catalyst of the invention has the advantages of low cost, simple preparation method, 
high activity, good selectivity, high safety in the operation of the aromatic ring hydrogenation, realization of the operation of the aromatic ring hydrogenation under a low pressure, and good economy.