Vascular channels are metastasis of cancer cells, cancer cells only in acidic conditions attached in the vascular wall surface adhesive molecule, can be transferred to other organs of the body. Chitosan oligosaccharide than cancer cells stronger adhesion effect (experiment has proved that chitosan oligosaccharide can direct role in cell surface), and on the chitosan oligosaccharide can promote the constitution to alkaline, thus to prevent cancer cells and molecules, the cancer cells lose transfer vector, thus inhibiting the metastasis of cancer cells.