Tm3+-doped glasses with the composition of (1-x)TeO2-xPbF(2), where x=10, 15, 20, 25 mol.% were synthesized and, their thermal and absorption measurements were investigated. All the glasses were transparent. The absorption bands corresponding to the absorption of the (1)G(4), F-3(2), F-3(3), F-3(4), H-3(5), and H-3(4) levels from the H-3(6) ground level of the Tm3+ ion were observed in the optical UV/VIS/NIR absorption measurements. We calculated the integrated absorption cross sections of each band except that of H-3(5) level was found to vary with composition of the PbF2. The absorption measurements were first made to determine the spontaneous emission probabilities of the 4f-4f transitions of the Tm3+ ions. The calculations were made by using the Judd - Ofelt theory. The Omega(2) parameter shows the strongest dependence on the host composition and it increases with the increasing PbF2 amount. The values Omega(4) increases rather slowly while the value of Omega(6) is practically independent of the composition. The strong dependence of the parameter Omega(2) indicates that this parameter is related to the structural change and symmetry of the local environment of the Tm3+ ions in this glass.