The present invention provides a method of measuring a width of a color filter unit of a liquid crystal panel. The method includes providing a bottom glass substrate having a TFT array thereon; forming the color filter plate locating within an effective region of the liquid crystal panel by photo-etching process, and forming one or more measure modules locating of the liquid crystal panel and on the TFT array by the photo-etching process; and measuring widths of the one or more measure modules out of the effective region to obtain the width of the filter units within the effective region. The method provided is capable of effectively controlling widths of the color filter units formed in process of manufacturing the liquid crystal panel, thus quality of the liquid crystal panel is raised.