Abstract: In a 0.2 mol/L NaOH solution,KIO₃ can yield two peaks at -0.6 V(vs.SCE) and -1.6 V on the cathode of oscillogram.The reduction at -1.6 V is quite sensitive,its depth would get shallow with the increase of Vc because of the reaction between Vc and KIO₃.Based on this oscillographic character,a new method,second order differential simple oscillographic voltammetry for the determination of Vc in a troche and a drink containing Vc is established in this paper.Under the optimal experimental condition,a linear response was observed in the range 3.0×10^-6~4.5×10^-5 mol/L with a correlation coefficient R=0.995 4 and a detection limit 2.0×10^-6 mol/L for Vc.The relative standard deviation (RSD) and average recovery for the determination of 3.0×10^-5 mol/L Vc are 2.9% and 98.9%(n=5),respec-tively.Thus,the oscillographic determination method in a redox system can be applied to the determination of some non-active substances in oscillographic analysis,and so it is an actually useful approach for enlarging the application field of oscillographic analysis.