A localized surface plasmon nanolithography (LSPN) technique is proposed and demonstrated to produce patterns with a sub-20nm line width. High transmission efficiency is realized by adjusting the period of grating. The well-regulated grating structures in metallic mask are employed to excite surface plasmon polaritons (SPPs) on the illuminated side. The SPP waves propagate toward the tip along the taper surfaces which cause most of energy accumulation at the tip and give rise to high local field enhancements in a near-field region around the tip. The amplitude of local electric field intensity is quite large and the line width can be confined within sub-20nm, at the same time, the contrast and spatial resolution are greatly enhanced, which can facilitate nanolithography efficiently with simple ultraviolet light sources. (c) 2007 Optical Society of America.