The improvement of hypoxia of tumor cells can effectively reduce their resistance to radiation and chemotherapy and im-prove the cure rate of the tumor. Recently, the compounds which are used to improve hypoxia of tumor cells and reduce radiation resist-ance are no longer just the original electrophilic radiosensitizers, and many potential targets as radiosensitizer for hypoxia also become research focus. Based on the mechanism of tumor hypoxia, the paper summarized the study progresses in four different radiosensitizers including new targeted agents, electrophilic radiotherapy sensitization agents, biological reductants and natural plant extracts.