Since the phenomena of Phatom limb pain had been discovered in the later ninteenth centries, its functional mechanism is not clear e- nough now and doesn't have a very effective therapeutic method. But this phenomena provides a good perspective for the research of epistemolo-gy. Using the theory of mental content can fully explain the phenomena of Pantom limb pain and the representation mechanism of mental con-tent , also it can enhance our understanding the riddle of cognition.