Influence of optical basicity on emission spectra at 1.45 μm of Tm3+ ions is investigated in alkali germanate glasses. The result shows that the bandwidth and intensity of emission spectra at 1.45 μm of Tm3+ depend on the optical basicity of the host glasses regardless of the glass systems. With the increasing in optical basicity, the 1.45 μm emission intensity decreased. It was found that the optical basicity calculated from glass composition may work as a guiding principle to obtain broadband fiber amplifier for wavelength division multiplexing systems.