The Judd-Ofelt parameters, oscillator strengths, radiative transition probability, radiative lifetime,quantum efficiency and upconversion coefficient of the Er 3+, Yb 3+ co-doped aluminosilicate glasses were calculated by the Judd-Ofelt theory, fluorescent lifetime and absorption spectra. The effect of Yb 3+ and Er 3+ ion concentrations, OH -groups on the spectroscopic and upconversion fluorescence properties was studied in this Er 3+, Yb 3+ co-doped aluminosilicate glass. It is found that at 1.56×10 20 cm -3 Yb3+ and Er3+ ion concentrations, the glass has the best spectroscopic properties.