A liquid crystal display (LCD) and an operating method thereof are provided. The operating method includes the following steps. It is determined whether a first frame and a second frame following the first frame are dynamic frames. When the first frame and the second frame are dynamic frames, a timing controller of the LCD performs a polarity inversion on a polarity signal, so that the polarity signal corresponding to the first frame is the same as the polarity signal corresponding to the second frame. When the second frame is written into an LCD panel of the LCD, energy written into the LCD panel is reduced.