Abstract: Objective: To explore the expression of ATP binding box subfamily C member 4 (ABCC4) gene in prostate cancer (PCa), and to analyze the effect of ABCC4 on the tumor immune microenvironment (TME) of PCa.Methods: Differentially expressed genes between PCa and paracancerous tissues were calculated using GEO2R from GEO database.The expression of ABCC4 gene in PCa was explored by GEPIA2 database.PCa da-ta of TCGA downloaded from UCSC Xena database were divided into high and low expression groups of ABCC4 gene.GO analysis and gene set enrichment analysis (GSEA) were performed using the clusterprofafiler R pack-age.TISIDB database, ESTIMATE and CIBERSORT were used to analyze the correlation between ABCC4 gene expression and immune indicators.Results: The ABCC4 gene expression in PCa tissues was higher than that in paracancer tissues (P< 0.05).The survival ability of PCa patients with high ABCC4 expression was poor.In GSEA, Th1 and Th2 cell differentiation pathways were activated in the low ABCC4 gene expression group, which hinted that ABCC4 gene might play a role in the TME of PCa.TISIDB analysis showed that ABCC4 gene expression was negatively correlated with NK and T cell abundance (P< 0.05).High expres-sion of ABCC4 gene was associated with low expression of immune checkpoint genes.ESTIMATE and CIBER-SORT analyses indicated that ABCC4 gene expression suppressed immune cell infiltration in PCa, especially CD8 T, NK, and Tregs cells.Immunofluorescence assay showed that low ABCC4 protein expression could in-duce more CD8 T cell infiltration(P< 0.05).Conclusion: ABCC4 gene regulates the infiltration of immune cells in the TME of PCa, especially the infiltration of T cells and NK cells, thus affecting the occurrence of PCa and its immunotherapy.