The invention, which belongs to the technical field of water purifiers, particularly relates to a water purifier display device and a control method thereof, and a water purifier. According to the control method, a light sensor detects ambient light information received by a display panel and the light information is sent to a controller; the controller processes the light information and determines the light intensity of the display panel; and the controller changes a display drive signal and adjusts the brightness of the display panel. Therefore, the display brightness is adjusted automatically based on the light. When the ambient light is dark, the brightness of the display panel is slightly reduced, so that phenomena that the light is too bright and the halo of the display icon occursare avoided and thus the display panel carries out displaying clearly. When the ambient light is bright, the display brightness is increased. Moreover, the functions, intelligence, and humanization ofthe water purifier are enhanced; and the user experience is improved.