Downconversion luminescence of one UV photon (320 nm) cut into two near-infrared photons (around 1 000 nm) was reported in Eu2+-Yb3+ co-doped phosphate glasses. Absorption, excitation and emission spectra were carried out to demonstrate the occurrence of quantum cutting in this system. The experimental evidences of the cooperative energy transfer from Eu2+ to Yb3+ were presented by the decay curves of 5d→4f emission of Eu2+ ions. Luminescence decay curves of Eu2+ emission were recorded as a function of the Yb3+ concentration and analyzed by using Inokuti-Hirayama′s model for energy transfer. Energy transfer efficiency was also calculated to be 23.05% for the Eu2+-1.0Yb3+ co-doped sample, and 53.6% increased for the Eu2+-2.0Yb3+ co-doped sample.