The work is aimed to study the processes of nonradiative energy transfer from Yb3+ ions to Tm3+ ions, as well as the processes of interaction between Tm3+ ions in Y2O3:Yb, Tm (CYb = 6, 10, 15 at. %, CTm = 1 at. %), Y2O3: Yb, Tm (СYb = 6, 10, 15 at. %, CTm = 3 at. %) ceramics.The luminescence spectra due to the 1G4→3H6, 1G4→3F4, 3F3→3H6, 3H4→3H6 transitions of the Tm3+ ions, as well as the luminescence decay curves from the 2F5/2 level of Yb3+ and 1G4, 3F3, 3H4, 3F4 levels of the Tm3+ ions recorded upon excitation of the level of the Yb3+ ions, were analyzed for concentration series Y2O3: Yb, Tm (CYb = 6, 10, 15 at. %, CTm = 1 at. %), Y2O3:Yb, Tm (СYb = 6, 10, 15 at. %, CTm = 3 at. %. %) ceramics. On the basis of this, the mechanisms of population and unloading of the corresponding levels of Tm3+ ions were proposed.