Abstract: To effectively control the surface temperatures of the discharge zone, a water-cooled non-thermal plasma reactor was designed, and he impacts of the operating voltage, frequency and air flow rate on the concentration of the active materials (O3, NO2) were investigated at different surface temperatures of the discharge zone. The chemical reaction mechanism was discussed. The results indicated that the discharge power was increased with the rising of VP-P, frequency and temperature, while the flow rate of air has little influence on it. The concentrations of O3 and NO2 were increased and then decreased as the air flow rate rising, with constant surface temperature of discharge zone. Reducing the surface temperature of the discharge zone can effectively improve the concentrations of O3 and NO2. These results provide a reference for reducing the diesel engine exhaust and regenerating diesel particulate filter in the indirect non-thermal plasma system.