This paper aims at discussing the problem of authorship of thefour essays in Kuan-Tzu. The conclusion we have is: four essays inKuan-Tzu are not produced by an unified school; they should bedivided into two sets of different schools. "Pai-Hsin" and "Hsin-Shu(I)" are works of the school of early Huang-Lao Taoism. "Nei-Yeh" and "Hsin-Shu (II)" are written by the Mencian scholars.Several accepted hypotheses in the past, such as "the theory ofSung Hsing-Yin Wan" and "the theory of Taoism" etc. are notreliable.