1. A driving circuit for driving a liquid crystal display (LCD), the driving circuit comprising a signal edge cutting circuit for implementing a signal edge cutting procedure of a scanning signal in order to eliminate a pixel charging voltage loss when the scanning signal is turned off, wherein the signal edge cutting circuit comprises: a first switch unit, for inputting the scanning signal; a second switch unit, for controlling either a turn-on status or a turn-off status of the first switch unit; and a third switch unit, for executing the signal edge cutting procedure; wherein the third switch unit decreases a voltage amplitude of the scanning signal by an edge-cutting resistor for implementing the signal edge cutting procedure of the scanning signal; wherein an input end of the first switch unit is coupled to the scanning signal and an output end of the first switch unit outputs the scanning signal; a control end of the first switch unit is coupled to an input end of the second switch unit, an output end of the second switch unit grounds, and a control end of the second switch unit is coupled to a first edge-cutting control signal; and an input end of the third switch unit couples to the output end of the first switch unit, an output end of the third switch unit grounds by way of the edge-cutting resistor, and a control end of the third switch unit couples to a second edge-cutting control signal; wherein a polarity of the first edge-cutting control signal is opposite to that of the second edge-cutting control signal; the first edge-cutting control signal and the second edge-cutting control signal are a square waveform with a duty cycle ratio of 0.5, respectively; wherein the signal edge cutting circuit further comprises a plurality of fourth switch units and an edge cutting selection chip; wherein the edge cutting selection chip transmits a turn-on signal to the fourth switch unit based on a gray level range of a display image to implement the signal edge cutting procedure of the scanning signal; wherein an input end of the fourth switch unit is coupled to the output end of the third switch unit, a control end of the fourth switch unit receives a turn-on signal, and an output end of the fourth switch unit grounds by way of the corresponding edge-cutting resistor; and wherein each of the fourth switch units has a different resistance.