Evaluating the kinetics of biological reaction occurring in confined nanospaces is of great significance in studying the molecular biological processes in vivo. Herein, we developed a nanochannel-based electrochemical reactor and a kinetic model to investigate the immunological reaction in confined nanochannels simply by the electrochemical method. As a result, except for the reaction kinetic constant that was previously studied, more insightful kinetic information such as the moving speed of the antibody and the immunological reaction progress in nanochannels were successfully revealed in a quantitative way for the first time. This study would not only pave the investigation of molecular biological processes in confined nanospaces but also be promising to extend to other fields such as biological detection and clinical diagnosis.