Breast cancer tends to have an increasing mortality, severely threatening the health of females. The invasion and metastasis of breast cancer are the leading causes of death. It has been reported that breast cancer is caused by the activation of a series of proto-oncogenes and inactivation of anti-oncogenes. In the present study, Real-time PCR and Western blot were used to detect the protein expression level of metadherin before and after transfecting MDA-MB-231 cells to identify the effect, while the sensitivity of MDA-MB-231 cells to 1 mg/L doxorubicin and 8mg/L taxol was measured by methylthiazolyldiphenyl-tetrazolium bromide (MTT). The results demonstrated that mRNA and protein expression level of metadherin both improved after transfection. The inhibition effect of 1 mg/L doxorubicin and 8 mg/L taxol on breast cancer cells decreased after transfection. Detected by flow cytometry, the apoptosis rate of breast cancer cells was 39.68±0.42%, 20.64±0.55%, respectively, under the effect of 1 mg/L doxorubicin; while under the effect of 8 mg/L taxol, the rate was 24.89±0.41% and 13.8±0.63%, respectively. Thus the inhibition effects of 1 mg/L doxorubicin and 8mg/L taxol to breast cancer cells and their effects on apoptosis were different, and the differences were statistically significant (P<0.05). Based on the statistics on the expression level of metadherin after transfecting breast cancer cells MDA-MB-231 and the exploration of the sensitivity of the cells to treatment, the effect of metadherin on breast cancer MDA-MB-232 cells was proved.