The invention relates to a preparation method of gold nanometer array electrode, which the substrate is polycarbonate filter membrane, after the processes of the pretreatment of chemical plating to the polycarbonate filter membrane, chemical plating, chemical plating after acid leaching, such as cleaning and processing, the former treatment, post acid leaching and rinsing, and assisted by the ultrasonic wave process in the steps of pretreatment, acid leaching and rinsing, using degreasing cotton soaked with dilute sodium cyanide to softly wipe the surface of the filter membrane after chemical plating, then rinsing with methanol, using the combined method of mechanical effect and chemical effect to effectively remove a gold layer on the surface to form the gold nanometer array, then pasting the filter membrane to the collector, assembling into the gold nanometer array electrode. The diameter of a single gold nanometer disk in the array is 10 to 100 nanometers measured by scanning electronic microscope, the component of the array group is pure gold measured with energy dispersive X-ray spectrum. The electrode has the advantages of high mass transfer speed, low double-layer charge current, effectively improving signal-to-noise ratio and the detection limit. The preparation method of gold nanometer array electrode has the advantages of ingenious design, simple operation and good reproduction.