The Er 3+-doped and Er 3+/Yb 3+-codoped tungsten-tellurite glasses were prepared. The absorption spectra, 1.5 μm emission spectra and fluorescence lifetime of Er 3+ excited at 970 nm, were measured. The absorption and emission cross-sections were calculated. The dependence of Yb 3+ concentration upon 1.5 μm emission intensity and bandwidth of Er 3+ were investigated. Yb 3+-codoping can improve the 1.5 μm emission intensity of Er 3+ effectively and increase its FWHM. The optimum Yb 3+ concentration was 3.66×10 20 ions/cm 3 and a broad 1.5 μm emission spectrum of 81nm FWHM was demonstrated.