Objective To investigate the difference of iNOS and NQO1 in breast cancer with different mo-lecular subtypes and the correlation between clinical parameters,and to explore the clinical treatment of breast can-cer. Methods The data on 100 patients with breast cancer who had undergone modified radical mastectomy was retrospectively reviewed.Expressions of iNOS and NQO1 were detected by immunohistochemistry.Numeration data was processed using χ2test or Fisher′s exact test.Spearman correlation was applied to analyze different clinical mo-lecular pathological features.Results NQO1 expression was correlated with TNM staging and lymph node metasta-sis(χ2=6.603,4.938,P<0.05),and the expression rate of NQO1 in overexpressing of HER-2 was higher than that in type luminal A(χ2=8.341,P < 0.008). Expression of iNOS was related to expression of Ki-67,stage of TNM and lymph node metastasis(χ2=5.243,8.157,and 5.929,P<0.05),the expression rate of iNOS in lumi-nal A was significantly lower than that in type luminal B(χ2=7.990,P<0.008).Conclusions The expression of NQO1 and iNOS may be involved the process of oxidative stress associated with breast cancer,and it plays an im-portant role in the development of breast cancer. Different molecular level of oxidative stress between the types of breast cancer may be different,whose molecular mechanism needs to be further studied.