The Eu3+–Y3+ double-doped Zr O2(8YSZ:Eu3+) phosphors with different doping concentrations of Eu3+ were synthesized by hydrothermal method. The dependences of the intensities of visible emission, decay lifetimes and crystal structures on Eu3+ doping concentration were investigated. The optimal doping concentration of Eu3+ in 8YSZ:Eu3+ nanophosphors was determined. The morphology and crystal structure of the resulting phosphors were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectra. The fluorescence properties of the resulting phosphors were investigated by photoluminescence spectra and decay curve. In this paper, 3 mol.% Eu3+ ions in 8YSZ:Eu3+ phosphors was the optimal doping concentration. When doping concentration was 3 mol.%, the nanophosphor had a pure tetragonal phase structure, the emission intensity was intense and decay lifetime was long, furthermore this system could be used to indicate the extent of phase transformation of thermal barrier coatings. The dependences of the intensities of visible emission, decay lifetimes and crystal structures on Eu3 + doping concentration were investigated. The optimal doping concentration of Eu3 + in 8YSZ: Eu3 + nanophosphors was determined. The morphology and crystal structure of the resulting phosphors were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectra. The fluorescence properties of the resulting phosphors were investigated by In this paper, 3 mol.% Eu3 + ions in 8YSZ: Eu3 + phosphors was the optimal doping concentration. When doping concentration was 3 mol.%, the nanophosphor had a pure tetragonal phase structure, the emission intensity was intense and decay lifetime was long, make this system could be used to indicate the extent of phase tra nsformation of thermal barrier coatings.