A backlight driving circuit includes a light emitting diode (LED) lightbar, a power supply driving the LED lightbar, a constant current driving chip controlling the power supply and the LED lightbar, and a control unit monitoring a voltage of a cathode of the LED lightbar. The constant current driving chip includes a main control unit that drives the power supply, and an adjusting unit that adjusts brightness of the LED lightbar. An input end of the adjusting unit is coupled to the cathode of the LED lightbar, and an output end of the adjusting unit is coupled to a load unit, a resistance value of the load unit may be adjusted. When the voltage of the cathode of the LED lightbar is greater than or equal to a preset threshold, the control unit controls the load unit to reduce the resistance value of the load unit.