Abstract: The technical field of catalysts, in particular to a combined catalyst and a preparation method thereof, and a method for preparing xylene by coupling carbon dioxide hydrogenation with toluene alkylation. The combined catalyst of the present disclosure having a metal oxide and a zeolite. In the present disclosure, the metal oxide is mainly used to reduce carbon dioxide to methanol, and the zeolite is mainly used to react toluene with methanol to produce xylene. When the catalyst of the present disclosure is used to prepare xylene, carbon dioxide and hydrogen can be used as raw materials instead of methanol. Compared with the traditional alkylation of toluene with methanol, this method can avoid the side reaction of methanol to olefins caused by the improper methanol/toluene feeding ratio, and improve the production efficiency of xylene; meanwhile, it can inhibit xylene isomerization and increase p-xylene selectivity in the products.