Use of 2-bromo-isovanillin in the preparation of an anticancer medicament and/or radio- and chemotherapy sensitizing medicament is disclosed. The medicament for the treatment of cancers and/or for radio- and chemotherapy sensitization comprising 2-bromo-isovanillin as active ingredient provided herein has the following features: (1) low toxicity, without evident adverse effects; (2) significant therapeutic effect, with remarkable proliferation inhibiting and pro-apoptotic effects in tumor cells; (3) a broad-spectrum anticancer activity; (4) suitable to be used in combination with antimetabolites, to enhance the effects and meanwhile lower the toxicity, and also to reduce multi-drug resistance; (5) convenient and safe administration, the main route being oral.