The invention relates to a liquid electrode surface discharge plasma reactor which is used for water treatment and consists of a flume, a discharge electrode system and a wastewater region, wherein, the discharge electrode system is positioned at the center of the flume, wastewater exists around the insulating medium tube of the discharge electrode system, the discharge electrode system is connected with the high pressure terminal of an alternating current high voltage source, the wastewater is taken as the liquid electrode which is connected with the low pressure terminal of the alternating current high voltage source, or the liquid electrode and the low pressure terminal of the alternating current high voltage source are simultaneously connected with ground wires, and aeration gas enters from the upper end of the insulating medium tube of the discharge electrode system, is ejected out from an aeration head at the lower end and then flows into the wastewater. When electricity is supplied by power, surface discharge plasma is produced on the inner wall of the medium tube, active materials are generated when the aeration gas passes through, and the active materials degrade pollutants in water and then treat the water. The liquid electrode surface discharge plasma reactor has the advantages of simple structure, high water treatment effect, low initial investment and small operation cost.