Abstract: Metal nanoparticles exhibited different physicochemical properties as compared to their bulk materials due to their high surface-to-volume ratio, which had a broad application prospect. However, the tendency of aggregation of nanoparticles must be overcome by using suitable capping agents. The capping agents played a significant role in stabilizing the metal nanoparticles and influenced their catalytic performance. Therefore, it's necessary to find the proper capping agents of metal nanoparticles. A facile and effective method to produce silver nanoparticles (Ag-NPs) in a water solution was reported. Cyclodextrin (CD), a soluble nontoxic molecule, was made up of six, seven, or eight glucose units, called α-, β-and γ-CD, respectively. Due to their unique hydrophobic cavities, CDs were used as an eco-friendly capping agent to stabilize the Ag-NPs by the hydrophobic interactions with the apolar primary faces of CD. In this paper, CD-capped silver nanoparticles were synthesized in an alkaline aqueous solution by reducing silver nitrate with CD and the synergetic catalytic effect between Ag-NP and different kinds of CDs was investigated. Then TEM, FT-IR and UV-vis spectroscopy were employed to characterize the synthesized Ag-NP. It was revealed that the size distributions of Ag-NP prepared in proper pH and CD concentration were quite uniform and could be controlled (10-30 nm). And a higher pH (pH>12) or lower CD concentration (c_CD<0.025 mmol/L) would lead to the aggregation of Ag-NP during the synthesis procedure. Recently, it was reported that the CDs and Ag-NP had cooperative catalytic activity during the 4-nitrophenol (4-NP) reduction reactions. During the reaction, the CD-capped Ag-NP had a strong catalytic effect on the reduction of 4-NP, and it was found that β-and γ-CD-capped Ag-NP had a better catalytic activity than that of α-CD-capped Ag-NP. The activation energy of β-CD-capped Ag-NP in the reduction of 4-NP was calculated to be 48.1 kJ/mol, which is lower than that of α-and γ-CD-capped Ag-NP.