Up-conversion luminescence of rare earth (RE) doped NaxGdyFx+3y glass-ceramics have become a meaningful subject due to their potential applications many fields.These RE fluorides glass-ceramics combine the advantages of fluoride nanocrystals and oxide glasses, especially the high chemical, mechanical and thermal stability [1].However, Na5Gd9F32, one type of sodium-gadolinium-fluoride NaxGdyFx+3y compound, has attracted few attentions, and only a few reports about nano-sized Na5Gd9F32 nanocrystals were reported, which is because of the poor thermal stability of nano-sized cubic Na5Gd9F32 phase [2].As mentioned above, nanocrystal phases in glass-ceramics are comparative stable due to their excellent thermal and mechanical stability.Therefore, its interesting and urgent to produce Na5Gd9F32 glass-ceramics with excellent thermal stability.In our work, Er3+-doped novel transparent Na5Gd9F32 glass-ceramics were fabricated.After heat-treatments, GC samples still maintain cubic Na5Gd9F32 phase, indicating the better thermal stability of Na5Gd9F32 glass-ceramics than nano-sized cubic Na5Gd9F32 spheres.Up-conversion mechanism and ET processes were systemically discussed in this work.The ET process is primarily responsible for up-conversion emission attributing to the fact that Er3+ ions incorporate into Na5Gd9F32 nanocrystals preferentially with shorter Er3+-Er3+ distances, lower phonon energy environment and higher crystallization degree.Meanwhile, these advantages reduce the multi-phonon non-radiative relaxation rate, and lead to the obvious Stark splitting, enhanced up-conversion luminescence (1300 times to PG) and longer lifetimes.Our investigation reveals this transparent and stable Na5Gd9F32 glass-ceramics may find potential applications in luminescent materials as one efficient up-conversion hosts for RE ions doping.