Thermal analysis and optical properties indicate that Tm3+ and Dy3+ co-doped oxyfluoride tellurite glasses can be excellent candidates for fiber amplifiers at 1.47 mu m region. Substitution of GeO2 and In2O3 in tellurite glasses increased the glass stability without decreasing the lifetime of the upper Tm3+:H-3(4) level, and the fluoride substitution increased lifetime of excited energy levels of Tm3+ ion. Dy3+ co-doping in the Tm3+-doped oxyfluo:appride tellurite glasses enhanced the depopulation of the Tm3+:F-3(4) level through an energy transfer Tm3+:F-3(4) --> Dy3+:(6)(H)over dot(11/2). We report the measurements of crystallization, glass transition temperatures, and optical properties of Tm3+, Dy3+ co-doped oxyfluoride tellurite glasses.