The invention discloses application of a thiourea molecule in preparation of antitumor drugs. The structural formula of the thiourea molecule is selected from formula I to formula IV, wherein R1, R2 and R3 are independently selected from hydrogen, alkyl with a carbon number of 1-10, aryl or a heteroatom group containing N, O and S. The invention provides new application of the thiourea molecule, specifically in preparation of anticancer drugs. The thiourea molecule is adopted as the anti-cancer drug, or is used as the active ingredient for preparation of pharmaceutical preparations, the antitumor drugs show very low cytotoxicity to human lung adenocarcinoma cells (A549), human breast cancer cells (BCap-37), human oral epidermoid carcinoma cells (KB), human lung fibroblast (HFL1) and human bronchial epithelial cells (BEAS-2B), but has very good antitumor effect at the animal level. (formula I, formula II, formula III, and formula IV).