Pathological angiogenesis is one of the most important stages for tumor growth and metastasis, thus inhibiting or blocking angiogenesis can interrupt the proliferation and migration of tumor cells.By doing this, an effective strategy of anti-tumor therapy can be taken.For this reason, finding new high performance anti-angiogenesis drugs have become a hot topic for cancer therapy.Human plasminogen that consists of five homoeomorphic kringle domains can be distributed into two anti-angiogenesis parts.The kringle 1 to kringle 4 domains called angiostatin is Part Ⅰ, and the kringle 5 domain which is closely resemble kringle 1,2,3,4 domain is Part Ⅱ.Substantial evidence has established that K5 is one of the most potent angiogenesis inhibitors, further more, the k5 have high specificity and a few side effect.Above all, Kringle 5 has great potential value and bright application future in tumor therapy.