The content of cephradine capsules was determined by a system of FOS-μSIA-LOV(fiber optic sensor-micro sequential injection-valve laboratory), based on the principle of cefradine quenching fluorescein in methanol solvent, optimize experimental conditions. The order of inhalation was anhydrous methanol, cefradine, fluorescein and anhydrous methanol; the carrier liquid suction volume was 500 μL; cefradine inhalation volume was 100 μL. Cefradine quenched fluorescein fluorescence intensity and concentration in 0.05～0.5 mg·mL-1 linear relationship as ΔF=812.6+284.41, r=0.999 5, precision RSD was 4.4%, the recovery was 101%～103%. FOS-SIA-LOV and personalized drug testing and programming resulted in automated on-line process analysis with the good reproducibility, less reagent consumption, time and labor saving.