A method for preparing an electrowetting display support plate (5), comprising the following steps: preparing a substrate (7) having an electrode layer; preparing a hydrophobic insulating layer (13) and pixel walls (20) on the substrate (7) having an electrode layer, the pixel walls (20) being made of a hydrophilic material; performing plasma etching on the substrate (7) having the pixel walls (20), the power of the plasma etching being 30-1,000 W/m2; and heating the substrate (7) subjected to the plasma etching, so as to recover the hydrophobicity of the hydrophobic insulating layer (13). According to the method, the technical bias that the display support plate (5) being treated by means of the plasma etching would influence the quality of the hydrophobic insulating layer (13) is eliminated.