Objective To investigate tumor-induced angiogenesis under the influence posed by the mechanical environments in and out of tumor, and simulate the capillary network numerically. Methods The tissue in and out of tumor is assumed to be linear visco-elastic. The diffusive coefficient of endothelia-cell (EC) keeps constant in normal tissue out of tumor. In tumor, the reduced activity of tumor cells becomes a big obstacle for EC's movement, the coefficient is supposed to be a power function along the distance from the tumor center. An equation for EC movement is established in this model to illustrate the mechanical effect. The capillary network is simulated numerically. Results A relatively realistic capillary network in and out of tumor is gained. The mechanical factor results a layered structure: at the edge of tumor, numerous capillaries are generated, while closer to the tumor center, less the capillary. A Necrotic Region without any vessel exists in the center. However, the model can not generate a layered network without considering the mechanical effect. Conclusion Different mechanical environments in and out of tumor play an important role in the process of tumor-induced angiogenesis.