A simple and effective approach to the aqueous phase synthesis of crystalline silver nanorods and nanowires is demonstrated, using which their diameters and spect ratios can be effectively controlled. The synthesis involves a template-less and non-seed process to high-quality nanoparticles, which is low-cost and proceeds at moderate temperatures. The nanorods and nanowires were synthesized by the reduction of silver nitrate with tri-sodium citrate in the presence of sodium dodecylsulfonate. The concentration of tri-sodium citrate plays a critical role while sodium dodecylsulfonate, as a capping agent, only plays an assistant role in controlling the diameters and aspect rations of the products. High-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) investigations show that the silver nanocrystals are generated with a twinned crystalline structure. We also put forward a primary experimental model to shed light on their growth mechanisms.