A series of silver colloidal dispersions were prepared by two protocols, i.e., addition of the reductant-NaBH4 and the stabilizer-thiosalicylic acid (TSA) into Ag+ solution simultaneously or successively. The products were compared and characterized by TEM, electrochemical measurements, XPS, UV-vis, and FT-IR spectra. The size distributions of the Ag nanoparticles prepared by the former and latter protocols are bimodal and monodisperse, respectively. The analytic results of UV-vis spectra coincide with the TEM observation. A tentative explanation was given to the relationship between particle sizes and different synthetic protocols. The changes of the reduction potential of the reductant invoked a variance in particle diameter and size distribution. Electrochemical measurements corroborated our assumption. The composition information of TSA-derived silver nanoparticles was obtained from XPS and FT-IR spectroscopic measurements.