In this study, the controllable fabrication of a variety of vertically aligned, single-crystalline -oriented Si nanowire arrays with sharp tips on (110)Si substrates is achieved using a combined self-assembled nanosphere lithography and multiple electroless Ag-catalyzed Si etching processes. All of the experiments were performed at room temperature. The morphological evolution and formation mechanism of long tapered Si nanowire arrays during the multiple tip-sharpening cycle processes have been investigated by scanning electron microscopy, transmission electron microscopy and water contact angle measurements. Field emission measurements demonstrate that the field-emission behaviors of all nanowire samples produced in this study agree well with the Fowler-Nordheim theory, and the produced long tapered Si nanowire array possesses superior electron emission characteristics, with a very low turn-on field of 1.4V/μm and a high field enhancement factor of 3816. The simple and room temperature fabrication of the well-ordered long tapered Si nanowire array and its excellent electron field emission performance suggest that it can serve as a good candidate for applications in high-performance Si-based vacuum electronic nanodevices.