The invention discloses a bimetallic complex catalyst and a preparation method and application thereof. The preparation method of the bimetallic complex catalyst comprises the following steps: separately preparing a mixed microemulsion of water-soluble metal salt and calcium chloride and a mixed microemulsion of water-soluble metal complex and water-soluble sulfate on the premise of ensuring solution transparence; mixing and reacting the two mixed microemulsion at a certain temperature under stirring condition to obtain a mixed microemulsion after reaction; aging and standing for a while to form a layer and particle coexisting structure in the mixed microemulsion obtained after the reaction; washing and centrifuging the mixed solution of organic solvent and water; and drying the precipitate to obtain the bimetallic complex catalyst. The catalyst obtained by the invention has good catalysis effect.