This paper reports on spectroscopic properties and energy transfer of Tm3+/Ho3+-codoped ZnO-WO3-TeO2 glass upon excitation of 808nm diode laser. The J-O strength parameters， spontaneous emission probability and radiative lifetime of Ho3+ were calculated using Judd-Ofelt theory. The absorption cross-section and stimulated emission cross-section were also investigated. Our result indicates that the highest gain of 2.0 μm emission, which comes from 5I7 to 5I8 transition of Ho3+, might be achieved from the glass at the rare-earth ion concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. It is found that coefficients of the forward Tm3+→Ho3+ energy transfer is about 18 times that for the backward Tm3+←Ho3+ energy transfer. The calculated fluorescence lifetime of the 5I7 level of Ho3+ is 3.9 ms and the emission cross section of the 5I7→5I8 transition of Ho3+ exhibits a maximum of 9.15×10-21 cm2 at 2027 nm. We also found that Tm3+/Ho3+-codoped tellurite glass is a promising host material for potential 2.0 μm laser by comparing the quantum efficiencies, the values of σe×τm and gain coefficients of fluoride and heavy metal oxide glasses respectively.