Abstract: Objective To observe the antiangiogenic effect of crocin on breast cancer and explore its possible mechanism. Methods In order to screen of appropriate drug concentrations, MTT assay was performed to test the inhibitory effect of crocin on breast cancer cell MDA-MB-231 and human umbilical vein endothelial cells（HUVECs）. The effect of crocin on MDA-MB-231 cell apoptosis and cell cycle was detected by flow cytometry. Transwell and Tubular formation test were used to detect the inhibitory of crocin on HUVECs migration and forming tubular. Nude mouse model of breast MDA-MB-231 cell was constracted, and the mice were given crocin（5 mg/ml） for 7 times. Immunohistochemistry was applied to detect CD34 and Ki-67 expression after MDA-MB-231 subcutaneous xeno-transplanted tumors treated with crocin. Results MTT method showed that crocin had a significant inhibitory effect on the proliferation of MDA-MB-231 cells（P＜0.05） and the IC50 of 48 h was 5.0 mg／ml. Crocin had a mild inhibitory effect on HUVECs without a dose-dependent manner at 24 h. But the effect was quite opposite at 48 h and 72 h， and the IC50 of 48 h was 5.97 mg／ml. Crocin induced the apoptosis and cell cycle arrest in G2／M phase of MDA-MB-231 cells in a dose-dependent manner（P＜0.05）. Transwell and Tubule formation test showed that crocin could inhibit HUVECs migration（P＜0.05） and tube formation（P＜0.05） in a dose-dependent manner. The subcutaneous transplantation tumor growth in 5 mg／ml crocin group was slower than that in blank control group. And the expression of CD34 and Ki-67 in blank group and 5 mg／ml crocin group were 26.00±2.65 and 14.67±4.16（P＜0.05）， 502.67±88.48 and 262.67±75.08（P＜0.05）. Conclusion Crocin has certain effect of anti-angiogenesis， which may be related to the inhibition of tumor cell proliferation， reduce the micro vascular density in vivo and can inhibit vascular endothelial cell proliferation， migration， as well as tubule formation in vitro. The exact molecular mechanism remains to study further.