By irradiating a Ag colloid solution, produced by trisodium citrate reduction method, employing the active Quanta Ray Nd:YAG laser system, lambda = 1064 nm, we prepared relatively small, spherical Ag nanoparticles with a narrow size distribution. The irradiated particles not only improve the configuration, but also the spectroscopy properties to some extent. The influence of the laser fluence on the irradiated energy was studied, via transmission electron micrograph (TEM) images, surface plasmon absorption (SPA) spectra, and surface-enhanced Raman scattering (SERS) spectra. Those benefit to understanding the spectroscopy properties of irradiated particles to obtain precise understanding of the mechanism. And probably the reasonable explanations are given. (c) 2006 Elsevier B.V. All rights reserved.