Objective: To separate and extract effective components from Viscum coloratum(Kom.) Nakai and investigate their effects on the proliferation of breast cancer cells. Methods: The classical separation and extraction methods were used firstly,and then according to different solubilities of alkaloids from Viscum coloratum(Kom.) Nakai in various solvents with different pHs,different components were extracted and obtained. The components were dissolved and cultured with breast cancer cells in vitro. Results: About 10 components were obtained and different inhibition effects were observed in co-culture with breast cancer cells. Component 5 inhibited the proliferation of breast cancer cells significantly in vitro and the IC50 for breast cancer cell line MDA-MB-435 and MDA-MB-231 was 3.24 mg/mL and 4.80 -滋g/ml,respectively. Conclusion:In vitro,series of extracts from Viscum coloratum(Kom) Nakai inhibited on breast cancer cells proliferation,and component 5 had significant inhibition effects on the cancer cells.