A gamma reference voltages generating circuit is disclosed in the present invention. The gamma reference voltages generating circuit comprises a voltage provider, a plurality of first digital-to-analog converters and a plurality of second digital-to-analog converters. The voltage provider generates a plurality of first supply voltages and a plurality of second supply voltages according to a first gamma reference voltage. The first digital-to-analog converters are electrically coupled to the first supply voltages for generating a plurality of second gamma reference voltages. The second digital-to-analog converters are electrically coupled to the second supply voltages for generating a plurality of third gamma reference voltages.