A pixel and an illuminating device thereof are provided. The pixel includes an organic light emitting diode (OLED), a transistor, a first switch, a second switch and a capacitor. One end of the OLED is electrically connected to a first voltage. A first source/drain of the transistor is electrically connected to a first potential point. The first switch is electrically connected between a second source/drain of the transistor and a second potential point, and is controlled by a first driving signal. The second switch is electrically connected between the second source/drain of the transistor and a gate of the transistor, and is controlled by a second driving signal. The capacitor is electrically connected between the gate of the transistor and a data line. The first driving signal and the second driving signal are used to alternately enable/disable the first and the second switches, so as to drive the pixel.