Absorption spectra, emission spectra and fluorescence lifetime were measured with different concentrations of Yb3+-doped, the emission cross section σe of Yb3+ was calculated. Dependence of luminescence intensity and fluorescence lifetime on concentration of Yb3+ was analyzed. No remarkable influence of concentration of Yb3+ ions on luminescence intensity and fluorescence lifetime was observed in the case of low level Yb3+ doped. Concentration quenching occurred when high level Yb3+ was doped. Luminescence intensity and fluorescence decreased because of it. The mechanism of concentration quenching was discussed and explained.