We fabricated a series of stable Er-doped CaO-Al2O3(Ga2O3) glasses by aerodynamic levitation (ADL) method. Using thermal analysis, we studied the influence of composition on the thermal stability of the glasses. The results unraveled the significance of composition on the stability of glasses. Magic angle spinning nuclear magnetic resonance (MAS-NMR) and Raman spectra were used to analyze the glass microstructure. The optical and spectroscopic properties were examined by UV-Vis absorption, steady-state fluorescence spectroscopy, transient state fluorescence spectroscopy, and luminescence quantum yield measurements. The results unraveled a clear concentration-dependent up-conversion and NIR emissions of Er3+, with obvious spectral broadening and redshift. The related mechanisms of decrease in fluorescent lifetime (from about 9ms to 2ms) and quantum yield (from about 75% to 5%) are discussed.