In this paper, the electrochemical behavior of the interaction of Reactive Brilliant Red K-2G (C.I. Reactive Red 15) with cyclodextrins in 0.1 mol · l−1 NaCl (pH 6.9) has been studied by polarography and voltammetry. In a supporting electrolyte of NaCl (pH 6.9), a sensitive second derivative reduction peak (i p ″) of Reactive Red 15 was found by linear sweep voltammetry (LSV). The peak potential is about −0.78 V (versus SCE). On the addition of CDs into the Reactive Red 15 solution, the reduction peak current (i p ″) of Reactive Red 15 decreases and the peak potential (E p ) shifts to a more positive potential. The study shows that Reactive Red 15 can form 1:1 inclusion complexes with nine CDs. The inclusion constants were calculated by “electric current method”. Furthermore, the inclusion ability of different kinds of cyclodextrins was compared, which provided some elemental data for application of Reactive Red 15 and cyclodextrins.