In this paper, effect of concentration of Rifampicin on the B-Z oscillating reaction and its application in rifampicin determination were studied. Experiment indicated that rifampicin had an effect on the shape, amplitude and period of the B-Z oscillating wave. The optimum condition and the concentrations of reactants were reported. A linear relationship was observed between the increase in the period of a single oscillation and the rifampicin concentration over the range from 2.49×10^-7 to 3.38×10^-5M, and the related coefficient is 0.9987 (N=18). Cyclic voltammetry was applied to study the mechanism of the proposed system.