Mechanical alloying of a mixture of Fe2O3 and Y2O3 was used in order to produce a single nanocrystalline YFe2O4 phase. After milling the diffraction characteristic peaks become broader and their relative intensity is reduced due to the particles size reduction and accumulation of microstrains. Diffraction peaks related to Y2O3 phase disappeared. After annealing at 1200°C, new peaks appeared and identified as Y3Fe5O12 phase. Magnetic properties measurements reveal that after annealing, saturation magnetization increased dramatically compared to as milled powders. Moreover, the Y3Fe5O12 shows a superferromagnetic behavior, with Ms ≈ 22 emu/g , Hc ≈ 14.5 Oe , Mr ≈ 1.56 emu/g and a crystallites size around 151 nm.