The invention discloses a backlight driving system, a backlight driving method and a display device, the backlight driving system comprises a power supply unit, a differential pressure waveform compiling unit, a driving unit and an output unit, and the power supply unit is used for providing voltage for the driving unit; the differential pressure waveform editing unit is used for generating a corresponding differential pressure waveform according to poor display and outputting the differential pressure waveform to the driving unit, and the differential pressure waveform comprises a differential pressure signal, a level signal and a clock signal; the driving unit is used for generating differential voltage and driving voltage according to the differential voltage waveform and transmitting the differential voltage and the driving voltage to the output unit together with a clock signal; and the output unit is used for controlling each LED light source of the backlight source in response to the received differential voltage, the driving voltage and the clock signal. According to the embodiment provided by the invention, the differential pressure waveform is generated according to different display defects, and each LED light source of the backlight source is independently controlled through the output unit, so that the display effect of the liquid crystal display panel is effectively improved.