Abstract: Objective To investigate the expression of suppressor with morphogenetic effect on genitalia-1（SMG 1），mammalian target of rapamycin（mTOR）and regulatoryassociated protein of mTOR（Raptor）in breast cancer and analyze their clinical significance. Methods From January 2014 to July 2015，samples of 68 breast cancer tissues，40 adjacent normal breast tissues，and 40 breast fibroadenoma tissues were collected. The expression of SMG 1 in the above tissues was detected by immunohistochemistry SP method. Real-time quantitative PCR（QPCR）was applied for the detection of mTOR and Raptor levels. Correlation of SMG 1，mTOR and Raptor with clinicopathological features of breast cancer was studied. Spearman correlation analysis was used to analyze the correlation between SMG 1 expression and mTOR, Raptor expression. Results The positive expression rate of SMG 1 in breast cancer tissues was 27.9％（19／68），lower than 77.5％（31／40） of adjacent normal breast tissues and 82.5％（33／40）of breast fibroadenoma tissues（P＜0.05）. The levels of mTOR and Raptor in breast cancer were 2.754±0.213 and 4.137±0.626，higher than those of adjacent normal breast tissues and breast fibroadenoma tissues（P＜0.05）. SMG 1 expression was related to tumor size，lymph node metastasis and histological grade（P＜0.05）. mTOR was related to tumor size， TNM stage and histological grade（P＜0.05）. Raptor expression was related to tumor size，lymph node metastasis and histological grade （P＜005）. SMG 1 expression was negatively correlated with mTOR and Raptor expression（r=-0.547，r=-0.415，P＜0.05），and mTOR expression was positively correlated with Raptor expression （r=0.664，P＜0.05）. Conclusion There are high expression of mTOR and Raptor, and low expression of SMG 1 in breast cancer tissues. Expression of mTOR，Raptor and SMG 1 are correlated with tumor size and histological grade，indicating that SMG 1, mTOR and Raptor may play an important role in the occurence and development of breast cancer.