Embodiments of the present disclosure provide a device and a method for controlling backlight, and a display device. The device for controlling backlight, comprising: a first controlling circuit configured to receive a first power supply signal for controlling a display device to be turned on or off, and generate an output signal for causing a backlight module of the display device to be turned off, in response to the first power supply signal being in a first status for controlling the display device to be turned off; and a second controlling circuit configured to receive the first power supply signal, and generate an output signal for causing the backlight module to be turned on again after being kept in a turned off state for a predetermined time period, in response to the first power supply signal being in a second status for controlling the display device to be turned on.