A backlight driving device and an operating method thereof are provided to drive multiple backlight zones of a backlight panel. The backlight driving device includes an interface circuit and a driving circuit. The interface circuit receives main backlight data corresponding to a first backlight zone from a former stage device. The driving circuit drives the first backlight zone according to a main current level in a display refresh period of a backlight frame period, does not drive the first backlight zone in a demotion blur period which is prior to the display refresh period, and drives the first backlight zone according to a compensation current level in a vertical blanking period which succeeds the display refresh period. The driving circuit determines the main current level according to the main backlight data, and the compensation current level is lower than the main current level.