BRAF mutation affects the biological characteristics and microenvironment of the tumor during the development of colorectal cancer. Tumor-associated lymph nodes are the key sites of immune response. This study aimed to systematically evaluate the impact of BRAF gene mutations on the remodeling of the CRC immune microenvironment, with a particular focus on their effects on the maturation and function of TLS·In this study, clinical samples of CRC patients were collected, and immune cell subsets were analyzed by single-cell RNA sequencing, and pseudo-temporal locus analysis and spatial transcriptome analysis were performed to explore intercellular communication and functional enrichment analysis. The distribution and maturity of TLS were evaluated by immunohistochemistry and multiple fluorescence staining techniques, and statistical analysis was performed.The results showed that BRAF mutation significantly affected the number and maturity of lymphatic structures infiltrated by tumors, and was negatively correlated with patient prognosis. BRAF mutations lead to alterations in T cell subsets, particularly the dual role of CD4+ CXCL13 cells in TLS maturation. B-cell subpopulation analysis revealed functional deficits in CRC patients with BRAF mutations, which further drove the remodeling of the tumor immune microenvironment.