Abstract: Objective:To study the relationship between the expression of heat shock protein 27(HSP27) in triple negative breast cancer (TNBC) and the clinico-pathological indexes of breast cancer, investigate the correlation between HSP 27and the fatty acid syn -thetase (FAS)/fatty acid synthetase ligand (FASL) of the cell apoptosis system in the Fas/Fasl system, and study the role of HSP 27in the invasion and metastasis of TNBC. Methods:The immunohistochemical S-P method was used to detect the expression of HSP27 and (FAS)/(FASL) in 100 TNBS tissue sampres,100 non-TNBS tissue sampres, and 50paraneoplastic tissues. This method was also used to analyze the correlations between the expression of HSP27and the clinical and pathological indexes of TNBC, as well as between the HSP27expression and FAS/FASL expression. Results: HSP 27expression was significantly higher in TNBC than in the non-TNBC and paraneoplastic tissues (P<0.05). Statistically significant differences were observed in the FAS/FASL expression in the TNBC, non-TNBC, and paraneoplastic tissues (P<0.05). HSP 27expression had a negative correlation with FAS expression ( P<0.05). HSP 27expression was positively correlated with FASL expression ( P<0.05). FAS expression had a negative correlation with FASL ex -pression ( P<0.05). HSP 27expression in TNBC was not correlated with age, staging, and tumor size (P>0.05), whereas HSP27expres -sion was correlated with lymph node metastasis, number of nodal metastases, and P 53and Ki 67expression ( P<0.05). Conclusion:The overexpression of HSP27and the expression dysregulation of the FAS/FASL system may play a role in promoting TNBC transfer and invasion, cell proliferation, and poor prognosis.