The present invention provides a pixel unit and a driving method thereof. By electrically connecting the source of the charge sharing thin film transistor to the scan line corresponding to the next row of sub pixels of the sub pixel where the charge sharing thin film transistor is and setting the voltage level of the scan line corresponding to the next row of sub pixels to be the array substrate common voltage when the sub pixel is scanned, the main region and the sub region of the sub pixel have different voltage levels, and the additional arrangement of a line of the array substrate common voltage is not required. In comparison with prior art, the number of wires in the array substrate is reduced and the aperture ratio of the liquid crystal display panel is increased which facilitates the realization of the narrow frame of the liquid crystal display panel.