Abstract: Objective To explore the role and molecular mechanism of major vault protein (MVP) in tumor-associated macrophages in the occurrence and development of liver cancer. Methods The mice with MVP deficiency in macrophages were constructed by Cre/LoxP recombinant enzyme system. The proliferation and migration ability of tumor cells were detected by the cloning formation and migration assays. The effect of MVP in macrophages on tumorigenesis and development was investigated by mouse primary liver cancer model and subcutaneous tumor transplantation model. The effect of MVP on tumor microenvironment was investigated by multi-fluorescent immunohistochemical staining. The effect of MVP on T cells was detected by cell co-culture, flow cytometry and qPCR assays. Results Cloning formation and migration experiments proved that MVP deficiency in macrophage promoted the proliferation and migration of tumor cells (P<0.05). The primary liver cancer model and subcutaneous tumor transplantation model demonstrated that MVP deficiency in macrophage promoted the development of tumor in vivo (P<0.05). Multiple fluorescent immunohistochemical staining indicated that MVP deficiency in macrophage would form an immunosuppressive microenvironment. Cell co-culture, flow cytometry, qPCR and Western blot assays demonstrated that MVP deficiency in macrophage weakened CD8⁺T cell-mediated anti-tumor immunity (P<0.05). Conclusion MVP deficiency in macrophage can promote the occurrence and development of liver cancer by affecting the recruitment and function of CD8⁺T cells.