Galactooligosaccharide ( GOS) is a kind of natural property of functional oligosaccharides, and its molecular structure is typically galactose, or glucose molecules connected to the 1 7 Gal, the Gal-(Gal) n -Glc Gal (n 0-6). In nature, animals, there are trace amounts of milk GOS, and were more content in breast milk, infant Bifidobacterium flora in the body to establish a large extent dependent on the GOS ingredient in breast milk.Galacto-oligosaccharide is the only 8 can be a great human intestinal bacteria for their use.