Dielectric barrier discharge can be used to produce non-thermal plasma at ordinary temperatures and pressures. The nitrogen（N2） and oxygen（O2） composed to nitrogen oxides（NOx）

water or some other solution can absorb it to become nitrate for the growth of crops and it is beneficial to achieve the low-carbon farming. This paper designs discharge nitrogen fixation system. By physical experimental means

supplemented by theory analysis and calculation

three factors which affect the product concentration are investigated. The three factors are discharge voltage

discharge frequency and discharge time. Under the conditions of the quality of the nitrate concentration as test indicators

the orthogonal experimental design is optimized. The experiment results are analyzed by single factor analysis

range analysis and the influence of single factors. The research shows that concentrations of nitrate ions increased significantly with the increase of the discharge time

there are obvious trend of decrease or increase with the change of discharge voltage

there is no obvious change trend with frequency.