-doped glasses are promising materials for green lasers working at a UV-excitation light. It is essential to find a commercially low-cost host with high quantum efficiency in the visible region. We report the preparation and optical characterization of a thermally stable and optically transparent phosphate glass containing silver nanoparticles with nominal composition (mol%) obtained by a melt-quenching technique and subsequent heat-treatments. The glasses are transparent in UV to near-infrared region and are not hygroscopic at ambient environment. The optical absorption and luminescence excitation spectra of the samples with and without silver nanoparticles are identical, and no sign of any silver species is revealed, while the luminescence spectrum is enhanced up to 1.7 times after heat-treating the samples for 15 h. The transmission electron microscopy and selected area diffraction pattern of glasses show the presence of silver nanoparticles with an average size of and growth at  crystallographic direction. The lifetime of the state of ions decreases from 3.06 to 2.85 ms by increasing the heat-treatment duration, which is indicative of the plasmonic effect of nanoparticles on the radiative rates of -doped glasses.