Objective: To investigate the silencing effects of amplified in breast cancer 1 (AIB1) gene via RNAi on the proliferation and apoptosis of triple-negative breast cancer cell line MDA-MB-231. Methods: According to cDNA sequence of the AIB1 gene, the shRNA which specified silencing AIB1 gene was designed and synthesized, then transfected into MDA-MB-231 cells. The expression levels of AIB1 gene was detected by Western blotting analysis after transfection. MTT assay was applied to evaluate the cell proliferation, flow cytometry assay was conducted to estimate cell apoptosis after being transfected. Results: Our experiments successfully built a recombinant expression plasmid which specified targeting AIB1 gene via RNAi in MDA-MB-231 cells. After transfecting, the protein relative levels of AIB1 in AIB1 gene silencing group were significantly lower as compared with the blank group (P<0.05). The OD value and apoptosis rate in AIB1 gene silencing group after 24, 48 and 72 h were 24.363±0.501, 32.596±0.348, 43.408±0.257 and (8.713±0.106)%, (11.396±0.147)%, (14.110±0.117)%, respectively, the difference were statistically significant between two groups (F=43.436, P<0.001; F=79.751, P<0.001). Conclusion: Silencing AIB1 gene can inhibit breast cancer cell proliferation and promote its apoptosis.