The invention relates to display technology, and provides a method and a device for calibrating luminance of a liquid crystal display aiming at the defects of no effective method for determining a boundary backlight value of a backlight source in the prior art. The method comprises the following steps of: setting an executing state, initializing and calibrating to determine the boundary backlightvalue of the liquid crystal display. The invention also provides a device for calibrating the luminance of the liquid crystal display. By the technical scheme, the backlight value corresponding to the boundary display luminance value of the liquid crystal display can be quickly set under the condition of no human intervention, and the set backlight value has small error and high precision; and the setting process is easy to implement.