The electrochemical coupling of water electrolysis and benzene hydrogenation reaction on platinum carbon (Pt-C) electrode was studied in the paper. The rules of reaction rate of electrochemical benzene hydrogenation were summarized through inspecting the influence of different reactant concentration, the reaction temperature and the cathode potential to the electrocatalytic hydrogenation reaction rate. The result of experiment displays that with the reactant concentration increasing;the electrocatalytic benzene hydrogenation reaction rate increases, however, the increasing tendency slows down while the reactant concentration reaches 25%; with the reaction temperature rising, the hydrogenations reaction rates speed up; activation energy of hydrogenations reaction is 32.88kJ/mol and activation energy of hydrogen evolution reaction is 18.08kJ/mol; with the step-down cathode potential, the total reaction rate speeds up remarkably and continuously, but the hydrogenation reaction rate reaches a maximum value, followed by a slight drop.