Using solution-based method, silver quantum clusters of different sizes (Ag 20 , Ag 140 and Ag 980 ) have been synthesized and their first hyper-polarizabilities were measured using hyper-Rayleigh scattering technique. We have shown that nonlinear optical properties of silver quantum cluster are highly dependent on the size of quantum cluster. Time-dependent density functional theory calculations using the Amsterdam Density Functional (ADF) program package are used to evaluate linear and nonlinear optical properties of silver tetrahedral Ag n (n=10, 20, 35, 56) clusters. Both theoretical and experimental data have shown that nonlinear as well as linear optical properties are highly dependent on the size of silver quantum cluster.