Abstract: With the increasing incidence and mortality of cancer, the limitations of conventional therapies have become increasingly apparent, necessitating the development of more precise immunotherapeutic approaches. mRNA vaccines have emerged as a prominent research focus in cancer immunotherapy due to their advantages in antigen design, rapid production, and enhanced safety profiles. This article reviews the advances in molecular design optimization of mRNA cancer vaccines such nucleoside modification, 5’-/3’-untranslated region (UTR) optimization and open reading frame (ORF) engineering to enhance efficacy and stability), key antigen types (viral antigens, tumor-associated antigens, tumor-specific antigens, and immunomodulators), delivery systems, and clinical research. By expressing specific antigens in vivo, these vaccines activate immune recognition and elimination of cancer cells. Currently, multiple mRNA vaccines have entered clinical trials, often in combination with immune checkpoint inhibitors or other immunotherapies. Despite their promising potential, challenges such as mRNA instability, difficulty in targeted delivery, immune tolerance, and tumor immune evasion still exist. Future breakthroughs will require advances in neoantigen prediction, targeted delivery, and combination therapy.