Summary Fu Si was a wonder in religion in Six Dynasties. Although he was not a monk，not a few of his disciples were monks and Taoist priests. He had never attended any school; however，he left some jih-suhng rich in Zen flavor. Because of this, he was deemed as a Zen harbinger.
Moreover，it was said that he came into being as Mulerbuddha, owing to his peculiar behavior. Fu Si had different images in different times. He was considered as a harbinger of Zen，but religious people in the Ten-Tai sect in Tan Dynasty found that his Zen ideas had a lot in common with theirs. After Tan Dynasty and Sung Dynasty，people thought him to be an upholder of san-jiauh-unite. After studying different biographies, I found another image of Fu Si. He was a missionary of Mullerbuddha's dogma in the southern Yangtze River in Six Dynasties. As a matter of fact，in his old age，he even urged his disciples to undergo intense acts of religious rituals, such as body-firing，finger-burning and so on. This kind of peculiar acts, however，was understand or omitted completely in most biographies.
Nevertheless, this paper was intended to inquire into the process of this missionary work in the southern Yangtze River and the causes of his different images.
