The invention discloses a diquat wastewater treatment method. The diquat wastewater treatment method comprises the following steps: (1) feeding diquat wastewater into a reaction kettle to adjust the pH value to 9.5-10.5; (2) adding an extractant into the reaction kettle; (3) starting stirring in the reaction kettle, and performing a reaction for 50-70 min; (4) stopping the stirring after the reaction is finished, and carrying out oil-water separation on the obtained product; and (5) continuously reusing the separated extractant until saturation. The method adopting an extraction process to treat the diquat wastewater is simple and easy, can avoid activated carbon from being used, and controls the concentration of 2,2-bipyridyl in effluent water at a low value, so the pressure of biochemical treatment in three-waste workshops is greatly reduced; and the extracted 2,2-bipyridyl can also be back-extracted, and is used for front-end reproduction to realize recycling, so the efficiency is improved, the production cost is saved greatly, and the method is a practical and efficient treatment method.