The invention provides an application of a eutectic compound composed of a proton pump inhibitor and a hydroxymethylglutaryl coenzyme A reductase inhibitor in preparation of an antitumor drug. The compound is characterized in that: the proton pump inhibitor is selected from one of omeprazole, esmeprazole, pantoprazole, rabeprazole and lansoprazole; and the hydroxymethylglutaryl coenzyme A reductase inhibitor is selected from one of atorvastatin, rosuvastatin, simvastatin, fluvastatin, pravastatin, lovastatin and pitavastatin or pharmaceutically acceptable salt of the atorvastatin, rosuvastatin, simvastatin, fluvastatin, pravastatin, lovastatin and pitavastatin. The antitumor drug can be used for treating one of liver cancer, lung cancer, stomach cancer, ovarian cancer, colon cancer, cervical cancer, oral squamous cell carcinoma and leukemia.