To study biological activity and mechanism of two modified anti-tumor peptide of tumstatin, the nucleotide sequences of 19peptide (amino acid185～203) and 21peptide based on modified T7 peptide (amio acid 75～95) of tumstatin were designed, artificially synthesized and inserted into the fusion protein vector pTYB2. After transformed and expressed in E. coli BL-21 (DE3) by means of fusion protein, the soluble 19peptide and 21peptide were obtained from one step chitin affinity chromatograph. By such experiment as MTT assay, cell growth curve, TUNEL assay，flow cytometry，the effect of the H22 ascitic fluid transfevent hepatoma of mice and histopathological slice, the biological activity of 19peptide and21peptide were studied. Experiments in vitro and in vivo identified that 19peptide could inhibit tumor cell proliferation, promote tumor cell apoptosis and stop tumor cell in G0/G1 cycle. It also could inhibit human umbilical vein endothelial cell proliferation to some extend. The anti-tumor activity of 19peptide mainly relied on affecting tumor cell directly and partly on inhibiting vascularization.21peptide inhibited proliferation of human umbilical vein endothelial cell much better than that of tumor cell. It almost could not promote endothelial cell and tumor cell apoptosis.21peptide mainly exhibited indirect anti-tumor activity by anti-angiogenesis. The combination of 19peptide and 21peptide obviously inhibited endothelial cell and tumor cell proliferation and promoted them apoptosis. A combination application could markedly enhance anti-tumor activity, make up the defect of 19peptide, 21peptide alone and bring about synergism. It would be an efficient method for tumor therapy in future, which will lay foundation on its mechanism of action research and clinical tumor therapy.