Near-infrared emission properties of Dy3+-Tm3+ co-doped Ge-Ga-Sb-Se glasses were investigated. Possible energy transfer routes and the regime of donor decay were discussed. Tm3+ is found to be an efficient sensitizer on the Dy3+:1.34μm luminescence. Probable energy transfer schemes include Tm3+:3H4 → Dy3+: 6F5/2 and Tm3+:3H5 → Dy3+:6F11/2· 6H9/2. The donor (Tm3+) excitation is transferred to an acceptor (Dy3+) by direct interaction or migrates among donors by diffusion-limited regime until it comes into the vicinity of an energy acceptor where direct interaction and transfer occur.