Abstract: AIM　To study the electrochemical behavior of ofloxacin at Pt/GC ion implantation modified electrode. METHODS　With Pt/GC ion implantation modified electrode as working electrode, the behavior of ofloxacin was studied by voltammetry in 0.40 mol·L^-1 KCl solution. RESULTS　A sensitive reductive peak of ofloxacin was obtained by linear sweep voltammetry. The peak potential was -1.35 V (vs SCE). The peak current was proportional to the concentration of ofloxacin over the range of 1.0×10^-6-3.0×10^-5 mol·L^-1 with the detection limit of 5.0×10^-7 mol·L^-1. The behavior of reduction wave was studied and applied to determination of ofloxacin in tablets. CONCLUSION　The reduction process was irreversible. The element composition, atomicity form and depth of distribution at the surface of Pt/GC electrode were determined by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and scannig electron microscope (SEM). The catalysis behavior and reaction mechanism at Pt/GC modified electrode was also studied.