Abstract: A fabrication method of a silicon nanoneedle array with ultra-high aspect ratio includes the following steps: spin-coating two photoresist layers of methyl methacrylate (MMA) and polymethyl methacrylate (PMMA) A2 on a silicon substrate; subjecting the silicon substrate coated with the two photoresist layers of MMA and PMMA A2 to electron beam lithography to form a photoresist pattern on the silicon substrate; subjecting the silicon substrate on which the photoresist pattern is formed to electron beam evaporation (EBE) to deposit an Al film layer on the silicon substrate; subjecting the silicon substrate on which the Al film layer is deposited to stripping to obtain an Al film array deposited on the silicon substrate, which provides a mask for the subsequent inductively coupled plasma (ICP) etching process; and subjecting the silicon substrate covered with the Al mask to ICP silicon etching to obtain a silicon nanoneedle array structure.