New fluorescent silica nanoparticles for sensors simultaneous determination of double targets were synthesized via a reverse microemulsion method based on the fluorescence resonance energy transfer(FRET).Nanoparticle A was doped with a dye complex which consisted of two dye molecules,fluorescein and tetramethylrhodamine.These dye molecules were first linked with avidin and biotin,respectively.They then formed a stable dye complex through avidin-biotin bridge within the distance of FRET.Nanoparticle B was doped with fluorescein only.As a result of this combination,the nanoparticles emit double wavelengths when a single excitation wavelength is used.The results show that the fluorescent nanoparticles are promising fluorescent labeling reagents for the sensitive detection of double targets.