The invention provides a nanoelectrode array which comprises a silicon wafer substrate 1, wherein a contour silicon tip array 2 is uniformly and vertically arranged on the silicon wafer substrate 1; a metallic thin film layer 3 is used for coating the surface of each of the silicon wafer substrate 1 on one side of the contour silicon tip array 2 and the surface of the contour silicon tip array 2; nano-particles 4 are arranged on the metallic thin film layer 3 located at the crest of the contour silicon tip array 2. The nanoelectrode array provided by the invention is small in size, large in density and small in tip curvature radius, and can be used for low-cost and large-scale preparation of ionization type sensors.