High near-infrared transparency Tm3+-doped germanate bulk glass and fiber have been fabricated and 2 μm emission properties demonstrated. Energy-transfer processes in the germanate glass and fiber are discussed. The emission spectra are obtained from both bulk glass and fiber with the excitation of a 794 nm laser diode. The results indicate that the line width of the Tm3+:3F4→3H6 emission spectra measured in fibers is narrower than that of the bulk glass sample and shifts to longer wavelengths with increment of fiber length. The extended overlap integral method is used to calculate the microparameters of energy transfer and critical distance. A model is derived to better understand of the energy-transfer process of thulium ions in the germanate glasses responsible for emission at 2 μm. The study indicates that Tm3+-doped germanate fibers with a large core diameter has proved to be promising infrared optical and high-power level laser materials.