Abstract: Objective To investigate the expressions of AIB1 and epithelialmesenchymal transition（EMT）-related proteins in invasive breast cancer and their correlations. Methods The expressions of AIB1， E-cadherin， N-cadherin in 80 cases with invasive breast cancer， 40 cases with breast fibroadenoma tissues， 40 cases with adjacent normal breast tissues were detected by immunohistochemisty. The relationship between the expressions of AIB1， EMT-related proteins and the clinicopathological characteristics was also analyzed. Results The positive expression rate of AIB1， E-cadherin， N-cadherin was 47.5％， 36.3％， 51.3％ respectively in invasive breast cancer. AIB1 was related with lymph node metastasis and molecular typing（P＜0.05）. E-cadherin was related with histological grade， lymph node metastasis， tumor size， TNM staging（P＜0.05）. N-cadherin was related with lymph node metastasis， TNM staging（P＜0.05）. The expressions of AIB1 and E-cadherin was negatively related， but the expression of AIB1 was positively related to HER-2 and N-cadherin. The expression of E-cadherin was positively correlated with the expression of ER. Conclusion AIB1 and EMT-related proteins may be involved in the occurrence and development， and AIB1 may regulate the expression of EMT-related proteins and play an important role in the process of invasion and metastasis of invasive breast cancer.