In pH 4.2-4.8 Britton-Robinson（B-R) buffer solution，moxifloxacin（MXFX) and gatifloxacin（GTF) of fluoroquinolone antibiotics（FLQs) could react with Cu（Ⅱ) to form chelate cations，which further bind with tetrachlorotetraiodo-fluoresceindisodium salt（Tf ) to form FLQs∶Cu（Ⅱ)∶Tf （ 1∶1∶1) ion association complexes.The system reactions resulted in the great enhancement of resonance Rayleigh scattering（RRS) and new RRS spectra appeared.The reaction systems of two drugs had similar spectral characteristics，the maximum RRS wavelength situated at 373 nm，and one small scattering peak situated at 590 nm.The intensities of RRS at 373 nm are proportional to the concentrations of antibiotics drugs in the ranges of 0.031-7.8 mg/L for MXFX and 0.029-9.0 mg/L for GTF.Based on this，a new method was developed for the determination of FLQs in capsule and human urine samples.The reaction mechanism and the reasons for RRS enhancement of the system were also investigated.