Abstract: The effects of the diameter of high-voltage electrode wire, the voltage of discharge, the structure of reactor and the total flow rate of H2-O₂ feed on the direct synthesis of hydrogen peroxide in ambient conditions by the dielectric barrier discharge (DBD) plasma method were studied.The results showed that the diameter of high-voltage electrode wire, the voltage of discharge and the structure of reactor had pronounced effects on H₂O₂ synthesis. By using a self-designed DBD plasma reactor (recycled flowing electrolyte as grounding electrode), H₂O₂ was synthesized with 32.51% yield at room temperature and atmospheric pressure from H₂-O₂ feed, which was several times higher than that reported in literature.