Disclosed are an LED backlight system and a display apparatus. The LED backlight system comprises an LED display module and an LED backlight control circuit. The LED display module comprises an LED light string. The LED backlight control circuit comprises a current module, a comparing unit, a control switch unit, and an impedance unit. An input end of the comparing unit obtains a voltage of a negative electrode end of the LED light string; when the voltage of the negative electrode end is higher than a preset threshold voltage, the control switch unit is controlled to be turned on to control the impedance unit and the current module to be connected in parallel, so as to reduce the voltage of the negative electrode end. By using the mode, the present invention can prevent the instability of a loop circuit, thereby preventing the phenomenon that the LED backlight system flickers.
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