Abstract: The controllable synthesis of AgNPs (nano-silver) with the same surface structures and different particle sizes is the basis for researching the AgNPs toxicity and risk assessment, which is one of the challenge in the material preparation. Chemical reduction was carried out by using silver nitrate (AgNO₃) as the reaction precursor, trisodium citrate (TSC) and sodium borohydride (NaBH₄) as stabilizers and reducing agents. One-step in-situ reaction to generate AgNPs with different particle sizes could be obtained through controlled synthesis parameters such as the dose ratio and the reaction conditions. Transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), inductively coupled plasma mass spectrometry (ICP-MS), Fourier transform infrared spectroscopy (FT-IR) and dynamic light scattering (DLS) were used to characterize the morphology and structural properties of the nanoparticles. The results showed that:(1) According to the TEM, it was found that the three AgNPs were spherical and had particle sizes of 12, 25 and 33 nm, respectively. (2) The UV-visible spectroscopy results show that the obtained product had strong absorption between 391 and 408 nm, indicating that the synthesized product was AgNPs. (3) The concentration of the unreacted silver ions, calculated by the results gained from ICP-MS, demonstrated the high yield of the preparation method (>99%). (4) DLS results confirmed that the synthetic AgNPs were negatively charged in aqueous solution and had a narrow particle size distribution. (5) FTIR shows the uniform surface structure of the AgNPs, which have the same functional groups such as carbon-carbon double bonds, ester, carboxyl and hydroxyl groups. In the preparation processes, the initial ratio of the solution, the reaction time and the environmental conditions had a great influence on the reaction results. This study indicated that the preparation process by the chemical reduction method was easy, reproducible and high yield. The series of AgNPs had uniform surface structure and good chemical stability.