The efficacy of current anti-tumor therapies has suffered from possible side effects and the poor accessibility of drugs to the tumor core. Although a variety of bacteria in nature have the potential to be used as anti-tumor drugs, lacking controllability and potential safety issues have limited their usage in tumor treatment. With the development of synthetic biology, bacteria are extensively programmed under engineering disciplines to possess less toxicity and enhanced ability to target tumors, sense the lesions and locate the lesions accurately. Applying engineered bacteria as vectors to directly carry drugs or express and release molecular therapeutics has greatly improved the efficacy of the tumor treatment. This article will summarize the recent progress in engineering bacteria for the treatment of tumors.