1. A method for detecting a ghosting effect of a liquid crystal display (LCD) having a plurality of pixel components, comprising the steps of: (a) providing a visual persistency period; (b) providing a maximum color alternation speed of the LCD; (c) obtaining a threshold value by multiplying the human visual persistency period by the maximum color alternation speed; (d) calculating a variation of an intensity level of each of the plurality of pixel components of the LCD; and (e) comparing the threshold value and the variation of the intensity level to obtain a comparison result to determine whether the ghosting effect exists in the pixel component.