This paper aims at discussing the problem of authorship of the four essays in Kuan-Tzu. The conclusion we have is: four essays in Kuan-Tzu are not produced by an unified school; they should be divided 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 of Sang using-Yin Wan” and ”the theory of Taoism” etc. are not reliable.