Abstract: Diesel engines are widely used in the field of industrial and agricultural production and transportation for their good economy and dynamic performance. However, with emission regulation becoming gradually stricter, how to reduce diesel particulate matter (PM) emissions effectively has become a growing concern of people. Diesel particulate filter (DPF) are considered to be the most effective means to reduce emissions of particulate matter, and the key of DPF lies in their regeneration. DPF regeneration is usually divided into two categories: active regeneration and passive regeneration. Active regeneration refers to the combustion of PM directly heated by external energy and the temperature is usually above 650℃. There are many methods of active regeneration, such as electric heating, microwave heating and combustion heating with the injected fuel. But there are many problems of these methods of regeneration, such as energy consumption, high cost and thermal damage of the carrier structure. Passive regeneration means to achieve regeneration by improving exhaust temperature to reach the minimum combustion temperature of the regeneration without the external auxiliary. There are many problems of passive regeneration problem, such as sulfur poisoning of the catalyst and low regeneration efficiency. Non-thermal plasma (NTP) technology can effectively remove the PM deposited in the DPF and it provides a new method for the DPF regeneration. The oxidation of the active substances produced by NTP reactor is stronger than O2 and PM can be well oxidized by these active substances. The working parameters of NTP reactor directly affect the concentration of the active substances, so suitable working parameters are conducive to the regeneration of active substances.This article discusses four working parameters of NTP reactor which affect the concentration of the active substances. The four factors are the surface temperature of discharge area, discharge voltage, discharge frequency and air flow. For the multi-factor experiment, orthogonal experimental design is an effective method of scientific experiments where part of the ones can reflect the comprehensive experiments. In this article, an experimental study on the performances of NTP Reactor was conducted, where air as the gas source. The optimal conditions of working parameters for Non-thermal plasma Reactor were determined by orthogonal design. Under the conditions of the concentration of O3 as the test indicators, the surface temperature of discharge area, discharge voltage, discharge frequency and air flow were optimized. The experiment results were analyzed by range analysis and variance analysis, and the influence of single factor was analyzed. The results revealed that the surface temperature of discharge area and air flow were remarkable factors, while the discharge frequency and discharge voltage had inapparent affection. Lower surface temperature of discharge area and discharge frequency would increase the concentrations of O3.With the increasing of air flow rate, the concentrations of O3 increases first and then decreases. There is no obvious trend of the concentrations of O3 with changes in discharge voltage. The effects on the concentration of O3 were in the order of air flow＞surface temperature of discharge area＞discharge frequency＞discharge voltage. The optimal combination were surface temperature of discharge area: 40℃, discharge voltage: 19kV, discharge frequency: 7 kHz, air flow: 5 L/min. It was proved by the experiment that the optimal combination was reliable and stable. The results obtained in this study has established the foundation for DPF regeneration based on non-thermal plasma technology. These results are of great significance for development of NTP system used to decompose the PM of diesel engines and optimization of DPF regeneration based on NTP Technology.