Gliding arc discharge process was used for the pretreatment of four azo dye solutions, which are classified to acidic, reactive and chemical indicator, as well as printing and dyeing wastewater with the objective of improving their overall biodegradability. The percentage color removal of all samples were found to be over 92% after 40 min treatment, and the color disappearance of four azo dyes followed the first-order kinetics completely. The biochemical oxygen demand (BOD5)/chemical oxygen demand (COD) ratio increased from 0.02 to 0.46 for acid orange II (AO7), 0.173 to 0.55 for methyl orange, 0.019 to 0.4 for direct fast black, 0 to 0.65 for reactive red K-2BP. The decolorization of printing and dyeing wastewater achieved 97.5% and the COD removal efficiency was 76.6%. The BOD5/COD ratio increased to 0.55 after 20 min treatment. The experimental results indicates it is possible to combine gliding arc discharge with conventional biological treatment for the remedy of wastewater containing generally non-biodegradable dye.