Objective:To evaluate the therapeutic effect of endostar(ED) combined with cisplatin(DDP) on model of C57BL/6 rats,and to further investigate the inhibiting mechanism of endostar from tumor angiogenesis.Methods:Lewis lung cancer cells were inoculated in C57BL/6 mouse,then the mouse were randomized into control group(group A),ED(group B),DDP(group C) and ED/DDP (group D).They were treated according to the plan.And the expressions of VEGF and Sema3A were evaluated by immunhistochemisty.Results:The weight of tumor increased in group A and B.It was decreased in group C and D.The tumor volume was increased in all the 4 groups. The VEGF expression of group D was obviously lower than the other group 3,but the Sema3A expressed of group D was significantly strengthener than the other group 3.The VEGF expression of group B and group D were obviously low especially in the 4th-8th days.Pearson correlated analysis showed that the expression VEGF and Sema3A were negatively correlated(r=-0.72, P<0.05).Conclusions:ED combined with DDP could control the tumor growth effectively,and avoid weight loss.ED could reduce VEGF expression,and enhance Sema3A expression.Tumor vessel presents transient normalization.It is easy for DDP perfusion,and to kill tumor cells. Objective: To evaluate the therapeutic effect of endostar (ED) combined with cisplatin (DDP) on model of C57BL / 6 rats, and to further investigate the inhibiting mechanism of endostar from tumor angiogenesis. Methods: Lewis lung cancer cells were inoculated in C57BL / 6 mouse, then the mouse were randomized into control group (group A), ED (group B), DDP (group C) and ED / DDP (group D) .They were treated according to the plan. And the expressions of VEGF and Sema3A were evaluated by immunhistochemisty. Results: The weight of tumor increased in group A and B. It was decreased in group C and D. The tumor volume was increased in all the 4 groups. The VEGF expression of group D was obviously lower than the other group 3, but the Sema3A expressed of group D was significantly stronger than that of the other group 3. The VEGF expression of group B and group D were obviously lower especially in the 4th-8th days. Pearson correlated analysis showed that the expression VEGF and Sema3A were negatively correlated (r = -0.72, P <0.05 ). CONCLUSION: ED combined with DDP could control the tumor growth effectively, and avoid weight loss. ED could reduce VEGF expression, and enhance Sema3A expression. Tumor vessel presents transient normalization. It is easy for DDP perfusion, and to kill tumor cells.