Objective:To observe the effect of endothelial protein C receptor(EPCR)on proliferation,migration and angiogenesis of human umbilical vein endothelial HUVECs cells,and to explore the role of EPCR in tumor angiogenesis. Methods:siRNA was performed to silence the expression of EPCR in human breast cancer cell line MDA-MB-231. The expression of EPCR in siRNA transfection was identified by reverse tansciption polymerse chain reaction(RT-PCR)and Western Blot. The experiment included three groups:the EPCR siRNA group,the irrelevant sequence group and the control group. HUVEC cells were cultured under tumor microenvironment,which was simulated by tumor conditioned medium. CCK-8 kit was performed to detect the endothelial cells proliferation,the transwell method was for detection of endothelial cell migration numbers,and matrigel in vitro small tube formation assay was performed to survey the state of tube formation. Results:The EPCR siRNA group showed lower cell proliferation activity,less number of cell migrats and tube formation than the other two groups (P﹤0.05). Conclusion:Low-expressed EPCR in human breast cancer cell line MDA-MB-231 can inhibit the proliferation,migration and angiogenesis of endothelial cells,which shows that EPCR may play an important role in tumor angiogenesis.