Objective:To explore the effect of down-regulation of γ-butyrobetaine hydroxylase 1(BBOX1)of patients with inva-sive breast cancer and correlation analysis of tumor immunity.Methods:The expression of BBOX1 in breast cancer was explored by TC-GA and GTEx database.And the relationship between the expression of BBOX1 and pathological features was analyzed by BcGenExMin-erv4.5 database and immunohistochemical methods.Kaplan-MeierPlotter database predicted the prognostic role of BBOX1 in breast cancer,and cancerSEA database evaluated the function of BBOX1 in breast cancer single cells.The Metascape database was used for GO enrichment and KEGG signaling pathway analysis.The TISIDB database was used to analyse of tumor chemotactic factors and tumor immunological cell infiltration related to breast cancer.Results:BBOX1 was highly expressed in breast cancer and its expression level was related to the formation of tumor immune microenvironment.Prognostic analysis showed that high expression of BBOX1 indicates worse recurrence free survival(RFS)and overall survival(OS).Single cell functional analysis revealed that BBOX1 expression was mainly related to angiogenesis,DNA repair,epithelial mesenchymal transformation,invasion,differentiation and stem cell characteristics in breast cancer.Conclusion:The abnormally high expression of BBOX1 in breast cancer indicates a poor prognosis and has a certain correlation with the formation of tumor immune microenvironment in breast cancer.