The purpose of this paper is to explore the mechanism of the angiogenesis modes in the biomaterials implanted in vivo. By means of experimental observation and analysis of the capillary growing state in the porous silk fibroin film implanted into rats, we intended to develop a modeling expression on the growth mode of the capillaries in the biomaterials. Additionally, we proposed the response model of endothelial cells (ECs) resulting from vascular endothelial growth factor's concentrations at different stages after the implantation. With the implantation experiment, it was identified that angiogenesis developed in the way of capillary sprouting at the early stage of implantation and of intussusception at the late stage. Based on the response model of ECs, experimental results are explained.