Rare earth doped phosphate luminescent nanoparticles were prepared in a Microreactor system in the ethylene glycol solution, using Ln(NO3)3·6H2O (Ln=Ce, Tb) and NaH2PO4·2H2O as raw materials. The crystal property, the shape and size of the particles of the LaPO4:Ce3+,Tb3+ nanoparticles were characterized by X-ray diffraction instrument(XRD), transmission electron microscopy(TEM). And the fluorescence property was detected by fluorescence spectrum instrument. The results indicated that the nanoparticles had hexagonal crystalline form, uniform particle size distribution and intensive fluorescence property