As one of the advanced oxidation processes (AOPs),the pulsed high-voltage electrical discharge draws much more attention on dye wastewater treatment in recent years.Especially the azo dye,it is one of dye which is difficult to degrade.In this work,degradation of azo dye (Acid Orange Ⅱ,AO7) by pulsed high-voltage electrical discharge with iron mesh was investigated.The effects of initial pH,the Fe2+ concentration,discharge mode,conductivity of initial aqueous solution and the type of bubbling gas (air,O2,N2) on the AO7 degradation were studied.The lower conductivity of aqueous solution and bubbling gas of O2 were benefit for degradation.The optimal treatment of AO7 degradation reached 79.6% at pH value of 2.28,Fe2+ concentration of 1.635mM.Gas-liquid discharge in a batch reactor(N-gas-liquid) with whose plate was in air and needles in liquid could be more effective than gas-liquid discharge and liquid discharge.Moreover,iron mesh-plate discharge was superior to multi-needle-plate discharge,in which the additional Fe2+ was unnecessary,and the degradation of AO7 was intensified by the special structure of iron mesh.