Abstract: OBJECTIVE To establish a method for determination of N-methyl piperazine and piperazine in ofloxacin and norfloxacin. METHODS The determination was carried out with Agilent HP CAM capillary column (30.0 m×0.25 mm, 0.25 μm) and FID detector. The inlet temperature was 230 ℃ and the detector temperature was 280 ℃. The column temperature rose by program: the initial temperature was 70 ℃, maintained for 3 min, raised to 180 ℃ with a rate of 40 ℃·min^-1, maintained for 2 min, The carries gas was nitrogen and the flow rate of carries gas was 2.0 mL·min^-1, the direct injection was used and the injection volume was 0.2 μL. The dissolved medium used was water and the internal standard was pyridine. RESULTS N-methyl piperazine and piperazine could be separated from internal standard in chromatogram obtained from system suitability test. The calibration curves were linear in the range of 10.09-201.88 μg·mL^-1(r=0.999 6) for N-methyl piperazine, 10.08-201.60 μg·mL^-1(r=0.999 5) for piperazine. CONCLUSION The repeatability and recovery met requirements, it can be applied in determination of N-methyl piperazine and piperazine in ofloxacin and norfloxacin.