This application belongs to the field of biomedical technology. This application discloses an antitumor agent and its application. The antitumor agent of this application comprises: (a) rosiglitazone; (b) one or more inhibitors for reducing the expression of fructose-1,6-bisphosphate aldolase C. The antitumor agent of this application can more effectively inhibit the proliferation of tumor cells and can be used as a potential antitumor agent.