A novel technique for YAG:Ln(Ln=Eu,Ce) phosphor powder synthesis with a nanocrystalline structure was developed.Nanocrystalline YAG:Ln powder was prepared by an ultrasonic atomization and co-precipitation method using a mixture solution of ammonium hydroxide(NH3·H2O) and ammonium hydrogen carbonate(NH4HCO3) as precipitant.The as-prepared nano-powders were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and fluorescence spectrometer.The obtained phosphor powders were homogenous and in size of 50-70 nm.The results demonstrated that by using ultrasonic atomization and co-precipitation process,we could synthesize a good quality YAG:Ln(Ln=Eu,Ce) phosphor powder that had many potential applications. A novel technique for YAG: Ln (Ln = Eu, Ce) phosphor powder synthesis with a nanocrystalline structure was developed. Nanocrystalline YAG: Ln powder was prepared by an ultrasonic atomization and co-precipitation method using a mixture solution of ammonium hydroxide H2O) and ammonium hydrogen carbonate (NH4HCO3) as precipitant.The as-prepared nano-powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and fluorescence spectrometer. The obtained phosphor powders were homogenous and in size of 50-70 nm. The results of that by using ultrasonic atomization and co-precipitation process, we could synthesize a good quality YAG: Ln (Ln = Eu, Ce) phosphor powder that had many potential applications.