This study demonstrates a facile but effective polyol-thermal reaction method for the synthesis of silver nanowires in autoclaves (160-180 ?C). By this approach, the generated silver nanowires show an average diameter of 40 nm and length up to tens of micrometers with a high yield and potential for large-scale production. To achieve shape- and size-controlled Ag nanowires, several experimental parameters were investigated and optimized, including surface controller(s), molar ratio of surfactant(s) to silver ions, temperature, and concentration of reactants. The structure and composition of silver nanowires were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. In particular, the twinned crystal structure observed in both spherical particles and nanowires was analyzed by HRTEM technique, and the possible formation and growth mechanisms were discussed. The optical property of the as-prepared product was measured by ultraviolet-visible (UV-vis) spectroscopy. The sensing detection of metal ions (e.g., Hg 2+) using the obtained silver nanowires in aqueous media was finally investigated.