Abstract: In recent years, the oceans have provided an important source of highly promising new anti-tumor drugs for innovation and screening, with approximately 56% of biologically active compounds being discovered to have anti-tumor effects each year. In this study, we classified and summarized the approved drugs of marine origin in terms of anti-tumor therapy, and firstly, we briefly overviewed the role of the immune system in cancer pathogenesis and discussed the current dilemma of cancer immunotherapy and highlighted the main anti-tumor targets of marine drugs. Further, with a focus on tumor immunity, we classified and outlined the history of currently approved marine original drugs by species origin, structural features, relevant pathways, and clinical application and therapy. Lastly, the limitations of current marine drug research were discussed, as well as prospects and trends in new drug development.