Tb3+-Mn2+-codoped zinc-strontium-phosphate glasses are prepared by the conventional melt-quenching method, and their photoluminescence spectroscopy is investigated as a function of the Mn 2+ concentration. It is observed that the excitation band at 350 nm due to Tb3+ overlaps that of Mn2+ ions, thus suitable for efficiently activating Tb3+-Mn2+-codoped glasses. The emission spectra of codoped glasses simultaneously show the blue (486 nm), green (541 and 582 nm), and red (617 nm) emissions. The 590 nm broad emissions of Mn2+ ions have been enhanced with the doping of Tb3+ ions, while the Tb3+ emissions have decreased with the increasing concentration of Mn2+. Decay curves of Tb3+ ions with the different concentrations of Mn2+ ions are also studied. The possible energy transfer process from Tb3+ to Mn2+ ions is proposed and the relevant mechanism is discussed.