Disclosed is a method and a device for driving a liquid crystal display panel. The method comprises the following steps. A first pixel signal of an image to be displayed is converted to a second pixel signal. An adjusted gray scale of each of sub-pixels and/or an adjusted backlight brightness of a backlight is acquired based on the second pixel signal and the first pixel signal. Each of the sub-pixels in the liquid crystal display panel is driven so that each of the sub-pixels can have a corresponding adjusted gray scale, and/or, the backlight is activated so that the backlight can have the adjusted backlight brightness. With the driving device and the driving method, it is able to ensure that when the RGBW liquid crystal display panel displays a solid colored image, the brightness of the image will not be reduced.