The present disclosure provides a device for reducing power consumption of a liquid crystal display, which includes: a screen area acquisition module for acquiring a first screen area being viewed and a second screen area not being viewed while a viewer watches a screen of the liquid crystal display; and a dynamic backlight control module for performing a dynamic backlight control adjustment on the second screen area. The present disclosure also discloses a method for reducing power consumption of the power consumption reduction device and a liquid crystal display having device. The present disclosure realizes intelligently partitioning dynamic backlight control to the screen of the liquid crystal display and also reduces the power consumption.