The water-soluble CdTe quantum dots(QDs) were synthesized in aqueous solution using 3-mercaptopropionic acid(MPA) as stabilizing agents.It was found that there was an appreciable overlap between excitation spectrum of CdTe QDs and absorption spectrum of tetracycline(TCs).Thus,the fluorescence inner filter effect(IFE) system was constructed between CdTe QDs(fluorophore) and TCs(absorber).Based on this IFE system,a synchronous fluorescence quenching method for the determination of TCs was developed.When Δλ was set at 220 nm,the maximum emission wavelength of synchronous fluorescence was 297 nm.Under the optimal conditions,a good linearity was obtained between quenched synchronous fluorescence intensity of CdTe QDs and concentration of TCs in the range of 1.0×10-6-1.0×10-5 mol?L-1.The correlation coefficient was 0.999 and the detection limit was 2.5×10-8 mol?L-1.With high sensitivity and good selectivity,the proposed method was successfully applied in the determination of TCs in milk samples with spiked recoveries of 97.0%-104.3%.