To develop new emission-tunable phosphors, a series of Ca2-yGd8-m-x(SiO4)(6)O-2:mCe(3+),xTb(3)+,yMn(2+) (CGS:mCe(3+),xTb(3+),yMn(2+), 0 <= m <= 0.56, 0 <= x <= 4.0, 0 <= y <= 0.4) samples were prepared by solid-state reaction method, and their photoluminescence properties were investigated. When the Ce3+, Tb3+ and Mn2+ ions are single-doped into the CGS host separately, the purple, green and orange emissions have been obtained, respectively. The energy transfer (ET) of Gd3+ Tb3+ Mn2+ was found in the CGS:Tb3+,Mn2+ phosphors, and the ET efficiency from Tb3+ to Mn2+ has been evaluated by using the Tb3+ decay lifetime. When the Ce3+ ions are introduced into the Tb3+-Mn2+ doped phosphors, an efficient ET from Ce3+ to Tb3+/Mn2+ occurs, and the emissions of Tb3+-Mn2+ are enhanced obviously. By studying the thermal quenching properties of the typical CGS:1.6Tb(3+),0.1Mn(2+) phosphor, it has been found that the Tb3+ and Mn2+ have different thermal stabilities, and the possible reason was discussed.