The present invention provides an overdriving circuit for source drivers to overdrive a LCD module. The overdriving circuit includes a first threshold detection logic unit, a second threshold detection logic unit, and a selection logic unit. The first threshold detection logic unit receives gray scale data from an overdriving timing controller, compares the gray scale data to a first predetermined gray scale value, and outputs a first control signal. The second threshold detection logic unit receives the gray scale data, compare the gray scale data to a second and a third predetermined gray scale values, and outputs a second control signal. The selection logic unit receives the gray scale data, receives a plurality of gray scale compensation data, and outputs one of the received data according to the first control signal, the second control signal and a third control signal.