A super twisted nematic (STN) liquid crystal display (LCD) driver and a driving method thereof includes a sub frame counter that counts the number of sub frames in response to a clock signal and generates a sub frame flag signal when each sub frame is counted. An N clock counter receives an N-line signal and generates an N-line flag signal when the number of N-line counted is N in response to the clock signal. A frame counter receives a frame rate control (FRC) selection signal, counts the number of the sub frame flag signal, and generates a frame flag signal when the number of the sub frame flag signal counted is n. A liquid crystal polarity inversion signal generator receives one of the sub frame flag signal, the N-line flag signal, and the frame flag signal in response to a selection signal, and generates a liquid crystal polarity inversion signal.