A liquid crystal display and a local dimming control method thereof are discussed. The liquid crystal display includes a liquid crystal display panel selectively displaying a 2D image and a 3D image in response to a mode signal, a backlight unit including a plurality of light sources, a backlight driving circuit individually driving a plurality of previously determined blocks each including the light sources based on a dimming value of each block, and a local dimming control circuit, that calculates a pixel gain value based on a dimming value of each block in a first frame, applies the pixel gain value to a data compensation for a second frame, which is arranged later than the first frame, and varies a time point when the pixel gain value for the data compensation is applied in response to the mode signal.