The absorption spectra and fluorescent spectra property of Cr3+, Yb3+, Er3+ co-doped phosphate glass were measured. Some basic properties of spectroscopic properties were calculated. The effect of Ce3+ and Cr3+ concentrations on the spectroscopic properties of the phosphate erbium glasses was also discussed. It could be concluded that the co-doped phosphate glasses of 2.8 mol-% CeO4 and 0.08 wt.-% Cr2O3 have the better spectral properties. On the other hand, the spectral properties are also affected by the valence change between the Ce3+ and Ce4+. Ce3+ is more favorable for the absorption of pumped light and energy transfer. The Cr3+, Yb3+, Er3+ co-doped phosphate erbium glass with fluorescent lifetime of 8 ms and stimulated emission cross section of 0.8×10-20 cm2 was achieved in the study. This provided good basis for the next laser experiments.