In this paper we demonstrate an approach to fabricate silica nanowires by combining "top-down" e-beam lithography and "bottom-up" layer-by-layer (LbL) nano self-assembly techniques. The simple and low-cost LbL self-assembly technique is used to grow silica nanoparticle thin film, while the e-beam lithography based lift-off technique is implemented to pattern the self-assembled thin film to nanometer scale. The silica nanowires fabricated by this method have an average width of 90 nm, while the minimum width obtained is 63 nm. Our experimental results indicate a new approach to fabricate nanowires that can be used in nanoelectronic devices and circuits.