A driving circuit of a backlight module is provided. The driving circuit has a dimming unit used for transmitting signals, wherein the dimming unit can adjust a current flowing through a light-emitting diode (LED) according a pulse width modulation signal and an enable signal, so as to adjust a light-emitting intensity of the LED. In the present invention, fewer devices are used to implement the dimming unit, and a transmission gate is replaced by a N-type transistor and a P-type transistor, such that a chip area and a circuit cost of the driving circuit are reduced.