The present disclosure relates to a source drive IC of liquid crystal panels. The source drive IC includes a digital signals module, a Gamma reference voltage module, a comparator, a power voltage module, a selector, a digital-to-analog converter (DAC) and a buffer amplifier. In addition, a driving method of liquid crystal panels may reduce the power consumption of the buffer amplifier to decrease the temperature of the source drive IC so as to enhance the reliability of the liquid crystal panel.