The tetraphosphate glasses with various Yb3+ dopant were prepared. The absorption and fluorescence emission spectra were measured. The spectroscopic properties and laser performance parameters of Yb3+ in tetraphosphate glasses were calculated. The disagreement between the reciprocity method and Fuchtbauer-Ladenburg formula was discussed using the radiation trapping effect. The effects of Yb3+ and OH- contents on emission properties were investigated. The result shows that Yb3+-doped tetraphosphate glass exhibits excellent spectroscopic properties.