The LED backlight source includes a boost circuit, a current control module, a voltage detection circuit. The boost circuit is configured for boosting an input voltage to an operation voltage needed by a LED string. The current control module connects to a negative end of the LED string to adjust an operation current of the LED string. The voltage detection circuit is configured for detecting whether the input voltage has been decreased, and for providing a control signals to a backlight driving control circuit upon determining the input voltage has been decreased. The backlight driving control circuit is configured for providing first square-wave signals to the boost circuit for boosting the voltage, for providing second square-wave signals to the current control module for adjusting a current, and for decreasing an input current upon receiving the control signals from the voltage detection circuit.