The present invention provides an over driving circuit of a liquid crystal display is provided. The circuit comprises a buffer, a memory coupling with the buffer and a modifier coupling with the buffer, the memory and a signal line. This signal line is used to transfer a row number signal to the modifier. The modifier may generate a corrected gray level value to a pixel unit based on a gray level value of present frame from the buffer, a gray level value of previous frame from the memory and the row number signal.