The present disclosure provides a dimming controller and a backlight module having the same, capable of distributing lighting times of each LED channel to a period of time. The dimming controller can decrease the duration of the LED string of each LED channel while maintaining under the duty cycle, thereby reducing the damage to the transistors. Besides, the dimming controller can turn on the transistors of the LED channels at different time points to avoid the higher current fluctuations at the output end, thereby reducing the flicker of the LED strings.