At room temperature, dielectric barrier discharge in air can produce non-thermal plasma with atmospheric pressure. Among the existed particles, there must be nitrogen and oxygen free radicals which combined as nitrogen oxides. The technology of non-thermal plasma nitrogen fixation was studied. Nitrogen oxides can be absorbed by water, and the nitrate solution can assist production of nitrogen fertilizer. In previous studies, The effects of time, voltage and frequency on nitrogen fixation were presented, and the subsequent discussion would be shown in this study. To eliminate error of absorption system, nitrogen oxide gas concentration was chosen as experiment detection index. Experimental factors included dielectric materials, dielectric thickness, discharge gap and peak to peak voltage. A four factors and three levels orthogonal experiment design method was used. Through range analysis of the experimental data, it showed that dielectric materials had the biggest effect on nitrogen oxide gas concentration. Through analyzing the average value of each factor, it showed that the optimal level for this experiment was quartz material, 5mm medium thickness, 2mm discharge gap and 30kV peak to peak voltage. Under the optimal level and discharge for 5min, gas concentration of nitrogen oxide was detected as 1004.20mg/m and the efficiency of nitrogen fixation was 2.21g/(kW·h).