OBJECTIVE To establish a HPLC-UV method for the determination of prulifloxacin and its related sustances in capsules.METHODS Using a Waters symmatry C₁₈ column(4.6 mm×250 mm,5 μm).The mobile phase consisted of 0.1% triethylamine(pH was adjusted to 2.8 using phosphoric acid)-acetomitrile(67.5∶32.5).The flow rate was 1.0 mL·min^-1 with UV detection at 275 nm.The column temperature was 25 ℃.The injection volume was 10 μL.RESULTS The linear range for the content of prulifloxacin was 0.50～10.00 mg·L^-1(r=0.999 3,n=5). The recoveries of prulifloxacin capsules were 101.2%,99.8%,98.2% and its RSDs were 1.2%,0.9% and 0.4%(n=5).CONCLUSION The method is sample,rapid,accurate and is suitable for the determination of prulifoxacin and its related substances.