The treatment of industrial wastewaters collected from petrochemical works, gypsum plant, and printing and dyeing mill, was investigated at atmospheric pressure in air discharge plasma. The degradation effects of organic contaminants in water were compared for the printing and dyeing wastewater under different discharging conditions and for the wastewater from the other two plants under the same discharging conditions. The influences of several factors on chemical oxygen demand (COD) remove rate were studied experimentally. The results showed that the treatment effects for the same industrial wastewater differed significant under different discharge conditions. There may be a suitable discharge plasma treatment to specific industrial wastewater. Due to the removal rates of COD of industrial wastewaters with discharge plasma isn’t very high, therefore the discharge plasma water treating needs to combine conventional water treating methods or addition other catalyst to effectively remove organic pollutants in wastewater and obtain the expected treatment effect.