Due to the complexity of tumor microenvironment，traditional cancer therapies have serious limitations，such as poor drug responsiveness，toxic side effects，difficulty in reaching deeper tumors，and tumors prone to recurrence. In recent years，bacterial - mediated cancer immunotherapy is attracting attention with its unique advantages. These bacteria preferentially colonize the hypoxic zone of tumors and kill tumor cells through various mechanisms，such as reshaping the tumor immune microenvironment and activating anti-tumor immunity. Based on this，genetic engineering techniques to construct recombinant antitumor strains that target tumors and secrete therapeutic proteins or nucleic acid drugs in the tumor core or in combination with other anticancer therapies are promising as a new cancer treatment strategy. This paper introduces the research progress of different antitumor bacteria and their clinical application status，and provides new ideas for bacterial immunotherapy of tumors.