A multi-tube parallel surface discharge plasma reactor has been designed to investigate its mineralization potential for organic wastewater. p-Nitrophenol (PNP) was used as the target pollutant. The effects of some operational parameters such as solution pH value, discharge voltage, air flow rate and air moisture on COD removal were investigated. Ozone utilization and biodegradability (BOD 5 /COD) of wastewater were evaluated. The results indicated that this discharge system presented a great potential for COD removal. For 40L of PNP wastewater, complete PNP removal and 97% of COD removal efficiency were achieved after 1h of discharge treatment with energy yield of 27.4g COD kWh −1 , and correspondingly, the ozone consumption and ozone utilization efficiency were 80% and 1.3g COD g O3 −1 . Increasing solution pH value and increasing discharge voltage were both beneficial for COD removal. The optimal air flow rate was observed as 1.5m 3 h −1 . Dry air contributed to a greater COD removal efficiency, due to more O 3 generation. The biodegradability of PNP wastewater increased up to 0.42 after 1h of treatment.