A method for detecting a bright dot or a dark dot in a LCD comprising applying a first detection voltage to a color filter substrate common electrode and forming a first voltage difference between the color filter substrate common electrode and a pixel electrode on an array substrate; collecting a first luminance value of the bright dot or the dark dot after the bright dot or the dark dot is observed; switching the first detection voltage applied to the color filter substrate common electrode to a second detection voltage, and thus forming a second voltage difference between the color filter substrate common electrode and the pixel electrode; collecting a second luminance value of the bright dot or the dark dot; determining the difference between the first luminance value and the second luminance value, so that the bright dot or the dark dot can be determined to result from a liquid crystal cell defect or an array substrate defect.