Disclosed herein is a local dimming driving method and device of an LCD device, which is capable of minimizing luminance deviation at the same gray scale due to a dimming difference between blocks. The local dimming driving method of the LCD device includes analyzing input image data in units of blocks and determining a local dimming value per block, performing spatial filtering with respect to the local dimming value per block, repeating spatial filtering by a predetermined repeat count, and controlling luminance of a backlight unit on a block-by-block basis using the local dimming value per block controlled by spatial filtering.