Objective: To observe the growth inhibiting and apoptosis induced by salvianolic acid B in human breast cancer cell line MCF-7. Method: Cultivation of MCF- 7 cell proliferation in vitro was determined,and using flow cytometry instrument for detection apoptosis rate and cell cycle changes Dan phenolic acid b on the MCF- 7 cell after 48 hours. Result: Salvianolic acid B can obviously inhibit the growth of MCF-7 cell dependent on dose and time; Flow cytometry instrument test results showed a gradual increase of the proportion of stage S cells and apoptosis rate after adding different concentrations of acids B. Conclusion: Salvianolic acid B has obvious growth inhibition and promoting apoptosis effect on MCF- 7 cell.