An exemplary liquid crystal display includes a plurality of pixel units each including a pixel electrode for receiving data voltages and a common electrode for receiving a common voltage having a constant value. The data voltages applied to each pixel electrodes are equal to a sum of a main data voltage having a square waveform and an auxiliary voltage that is periodically changed at intervals each formed by four continuous frames. An absolute value of the auxiliary voltage is less than a voltage difference between the main data voltage and the common voltage, a sum of the auxiliary voltage is zero in a minimum period.