Some conditions are put forward about improving the up-conversion efficiency through study of oxy-fluoride glasses based on TeO2,GeO2,ZnF2,SiO2 and PbF2. Hosts with low phonon energy benefit the energy up-conversion.It is also found that when the value of the quasi-field parameter of the oxy-fluoride host is adjusted near to that of the M parameter of the doped rare-earth, the materials show high up-conversion efficiency.Selecting suitable excitation photon energy to match the level of rare-earth ions and/or sensibilizer ions is a necessary condition for high up-conversion efficiency.The results provide some practical guidance to prepare rare-earth doped energy up-conversion materials.