The nitrate contamination has greatly affected the quality of groundwater and threatened the safty of drinking water at present. The paper used electrolysis method to removal nitrate in water body,and investigated the mechanism, kinetics, impact factors and treatment method of underground water.The method can provide reference for the removal of nitrate from groundwater.Experiment results showed that when 30.0 mg/L nitrate solution was electrolyzed under 2.0 A, the first order kinetic constant is 0.040 h-1, and 54% of product is ammonia and 46% of that is gaseous nitrogen under the system without chloride ion. When 300.0 mg/L chloride ion is added into the system, the first order kinetic constant is reduced to 0.029 h-1，and the main products are nitrogen. Moreover, the removal rate of nitrate is increased with the increase of initial nitrate concentration and current, but decreased with the increase of chloride ion concentration. The treatment of underground by electrolysis showed that when 20.0 mg/L nitrate is electrolyzed under 2.0 A and 100.0 mg/L chloride ion, the first order kinetic constant is 0.031 h-1, and the main products are gaseous nitrogen. The electrode efficiency of nitrate is lower due to the slow diffusion rate of nitrate to cathode in the process of two-dimensional electrode.