To explore the role of DNA repair gene ERCC1 in breast cancer metastasis and its signaling pathway.Through prospective cohort studies and cell tests, Western Blot and IHC were used to detect the expression of DNA repair gene ERCC1 and NF-κB signaling pathways related proteins, scratch test and Transwell to detect the ability of migration and invasion. To explore the mechanism of ERCC1 affecting breast cancer metastasis. Population results: There was no significant difference in clinicopathological features between the two groups (P > 0.05). ERCC1 has a positive correlation with breast cancer metastasis(r = 0.543, P < 0.05). And the metastasis-free survival rate of ERCC1 low expression group was higher than that of high expression group(Χ2 = 17.571, P < 0.05). The expression level of p65,p50,TNFα,IKKβ in ERCC1 low expression group was significantly lower than that in ERCC1 high expression group(P < 0.05), IκBα was significantly higher than ERCC1 high expression group(P < 0.05). The analysis of Spearman correlation method shows that ERCC1 expression is positively correlated with the IKKβ(r = 0.481, P < 0.05), IKKβ and IκBα were negatively correlated(r = -0.203, P < 0.05), IκBα and p50 were negatively correlated(r = -0.275, P < 0.05), p50 and p65 were positively correlated(r = 0.386, P < 0.05), positive correlation between p65 and TNFα(r = 0.476, P < 0.05), TNFα is positively associated with breast cancer metastasis(r = 0.281, P < 0.05). Cell tests:At 24 hours, the migration distance of the MCF-7-ERCC1 knockdown group was less than that of the negative control group(P < 0.05). At 48 hours, the migration distance of MCF-7-ERCC1 knockdown group was less than that of blank control group and negative control group(P < 0.05). Compared with the blank control group and the negative control group, the number of cell invasion in the MCF-7-ERCC1 knockdown group decreased significantly (P < 0.001). Compared with the blank control group, the number of cell invasion decreased in the negative control group(P < 0.05). The protein level of p65, p50, TNFα, IKKβ in ERCC1 knockdown group was significantly lower than that in blank control group and negative control group(P < 0.05), IκBα protein levels were significantly higher than those of the blank and negative control groups(P < 0.05). DNA repair gene ERCC1 may affect breast cancer metastasis by regulating NF-κB signaling pathways.