Abstract: It was found that in an alkaline solution,chemiluminescence,produced by the reaction system of luminol-KIO4-Co2+,was remarkably inhibited by the presence of ciprofloxacin,and the magnitude of decrease of chemiluminescence intensity was found to be directly proportional to the concentration of ciprofloxacin.Based on these facts,a method of FI-chemiluminescence determination of ciprofloxacin was proposed.Linearity was kept in the range 3.0×10-7-1.0×10-5g·L-1 with a detection limit of 2.0×10-7g·L-1.Precision of the method was tested at the concentration level of 1.0×10-6g·L-1 and the RSD′s (n=11) found was 2.7%.The proposed was applied to the analysis of ciprofloxacin tablets,giving values of recovery in the range 98.5%-101.2%,and the analytical result obtained was in conformity with the result obtained by the method of chinese pharmacopoeia.