The present invention discloses a display panel driving device and a driving method thereof, wherein the display panel driving device includes a plurality of mapping table units and a source driver. The mapping table units receive a plurality of primary color signals respectively, and convert grayscale levels of the primary colors into a plurality of mapping grayscale level values corresponding to a single gamma curve according to the grayscale level mapping relation between the single gamma curve and a plurality of primary color gamma curves. The source driver is electrically connected to the mapping table units to receive the mapping grayscale level values generated by the mapping table units, and convert the mapping grayscale level values into a plurality of driving voltages according to the relation between grayscale levels and voltages of the single gamma curve for inputting the driving voltages into a display panel.