Silver nanoparticles with homogeneous size and density were deposited on the surface of a cellulose triacetate film through chemical dipping and photoreduction. UV-VIS absorption spectra and high resolution transmission electron microscopy (HRTEM) show that spherical silver nanoparticles with 2—5nm diameter were formed effectively at room temperature by properly modulating the concentration. By contact copying technique, holographic gratings were constructed with metallic nanoparticles embedded in the polymer film.