A digital photo frame (DPF) includes a power source, a display panel, a light detector, a motion detector, a processing unit, and a power management unit. The light detector is configured to detect the ambient brightness. The motion detection unit is configured to detect whether anyone is around. The processing unit is connected to the light detector and the motion detector. If the motion detector detects someone is around the DPF and the light detector detects the ambient brightness is below a predetermined value, the processing unit controls the power management unit to provide power to the display panel.