The kinetics and mechanism in the electrochemistry/catalytic hydrogenation (E/C) coupling process, which was employed to remove nitrate (NO₃^--N) from groundwater, was investigated in this paper. The results demonstrated that the NO₃^--N could be rapidly removed by E/C under anoxic conditions, and the degradation efficiency of NO₃^--N followed the increasing current density(I_D) with observed second order reaction rate and the constant(k) value of 0.005 5 cm²·mA^-1·min^-1. The NO₃^--N reductive by E/C with two kinds of reactions, electrochemistry denitrification and catalytic reduction, both of which aggregated by the reaction of brine electrolysis.