In this paper, we present a top-down fabrication method of single-crystal silicon nanowires. The method employs the popular photolithography technique and etching-rate dependent on the crystal orientation of single-crystal silicon in KOH solution. Using surface wet adhesion and reduced silicon dioxide etching, nanoscale SiO₂ mask line patterns with width from 45 nm to 200 nm and length up to 120 µm are successfully patterned.