A micro/nanofluidic preconcentration device combined with fluorescence resonance energy transfer (FRET) technique using gold nanoparticles (AuNPs) as quenchers has been developed for detection of trace amount of protein.The sample protein is first mixed with AuNPs,then the fluorescently labeled competitor protein are added,competing with the surfaces of AuNPs.The protein concentration is determined by the magnitude of fluorescence enriched by micro/nanofluidics device.Since the micro/nanofluidic chip has a highly efficient concentration capacity of about 103-105 fold of initial sample concentration,the fluorescence changes corresponding different concentrations of sample protein can be amplified as large as 103-105 fold.Using this method,a trace concentration of protein as low as 1.5 pM can be successfully detected,which is more than 100-fold lower than that reported for most sensitive commercial protein quantification methods.