The present invention relates to a driving circuit of a display panel. A plurality of driving units produce a reference driving voltage according to a gamma voltage of a gamma circuit, respectively. A plurality of digital-to-analog converting circuits receive the reference driving voltages output by the plurality of driving units, and select one of the plurality of reference driving voltage as a data driving voltage according to pixel data, respectively. The plurality of digital-to-analog converting circuits transmit the plurality of data driving voltages to the display panel for displaying images. A voltage boost circuit is used for producing a first supply voltage and providing the first supply voltage to the plurality of digital-to-analog converting circuits. At least a voltage boost unit is used for producing a second supply voltage and providing the second supply voltage to the plurality of driving units.