The invention discloses a method for synthesizing a water-soluble one-dimension gold-palladium alloy nanowire. The method comprises the following steps: (1) preparing a sodium citrate solution, a chloroauric acid solution and a sodium chloropalladite solution; (2) mixing the sodium chloropalladite solution, the chloroauric acid solution and water to form a premixed solution; (3) adding the premixed solution into water to form a reaction solution; (4) adding the sodium chloropalladite solution into the reaction solution, and stirring at the room temperature to obtain a one-dimensional gold-palladium alloy nanowire structure which has uniform appearance and high ethanol catalyzing performance. By adopting the method, a component-adjustable water-soluble gold-palladium alloy nanometer novel structure is prepared by one-step under-potential deposition on a gold nanowire generated in situ by reducing chloroauric acid in the sodium citrate with palladium; compared with other synthesizing methods, the method is easy to operate, and can be used for obtaining a high-quality, component-adjustable and water-soluble one-dimensional gold-palladium alloy nanowire structure which cannot be obtained by other conventional methods.