Vibrational strong coupling (VSC) has a remarkable ability to induce molecular energy level changes, which offers great potential for effective control of chemical reactions, especially electrochemical processes. However, there are few reports about redox processes in optical microcavities. The oxidation-reduction reaction of potassium ferricyanide on the surface of gold electrode was a classical reaction in electrochemistry. In order to study the effect of vibrational coupling on the oxidation reaction of potassium ferricyanide on the surface of gold electrode, an electrochemical micro-cavity was designed as an optical resonator and the oxidation reaction of potassium ferricyanide on the surface of gold electrode was studied. The experimental results show that the oxidation efficiency of potassium ferricyanide is consistent with the O―H vibration band. Under the VSC of 3420 cm^–1 O―H stretching vibration, the O―H Rabi splitting affects the interaction between water molecules and changes the hydration of ions, so the oxidation efficiency of potassium ferricyanide is inhibited by about 52% compared with non-cavity system. This work provides a novel and more efficient physical means for regulating chemical reactions. More importantly, the integration of electrochemistry and microcavities enables real-time monitoring of reaction processes, addresses the challenge of detecting limited quantities of samples within a finite space.