The invention relates to a washing power-assisting device, and belongs to the technical field of washing. The washing power-assisting device comprises an electrolysis power supply and a water quality adjustment unit arranged on the outside of a washing device, wherein the water quality adjustment unit comprises at least a cathode electrode and an anode electrode in pairs, the electrolysis power supply is used for supplying power to the cathode electrode and the anode electrode, a water-pervious diaphragm is arranged between the cathode electrode and the anode electrode which are in pair, the water-pervious hole diameter of the water-pervious diaphragm is smaller than or equal to 2 millimeters and larger than or equal to 1 nanometer, and the distance between the cathode electrode and the anode electrode is larger than or equal to the thickness of the water-pervious diaphragm and smaller than or equal to 20 millimeters. The washing power-assisting device can generate a large number of ultramicro bubbles whose content is mainly hydrogen and super-oxidized factors and has good reducing washing water; a water in-out port of the water quality adjustment unit and the external washing device form a sealed water supply and discharge channel, circulating water flow is maintained in the washing process, water quality is adjusted continuously, and the effects of using washing agents as few as possible or even being free of using the washing agents, saving water and reducing emission are achieved.