The surface of (Y,Gd)BO3:Eu3+ phosphor, a red-emitting source in the plasma display panel (PDP), was coated with Al2O3 nano-particles. Colloidal alumina oxide was selected as a coating material for the surface modification of the (Y,Gd)BO3:Eu3+ phosphor. A modified sol-gel method was used for coating the surface of the phosphor by Al2O3 nano-particles. Al2O3 nano-particles in the surface of the phosphor were observed by Scanning Electron Microscope. It was found that the luminance intensity was increased in the photo-luminescence (PL) by a suppression of the nonradiative recombination via surface defeats. The experimental results suggest that the surface coating of phosphors with Al2O3 nano-particles leads to an increase in the luminance intensity of the PDP and the gas discharge lamps.