Doxorubicin (DOX) is widely used as a chemotherapeutic agent for liver cancer. However, its clinical applications are greatly restricted by its nonselective cytotoxicity. A novel magnetic prodrug, Fe₃O₄@DOX, was designed, synthesized and characterized, and Fe₃O₄ and DOX were connected by the peptide CGGAAN. The magnetic prodrug Fe₃O₄@DOX was successfully synthesized with average sizes of 95 nm and 322.5 nm by TEM (transmission electron microscopy) and Malvern Zetasizer instrument respectively. The maximum emission wavelength shifted from 594 nm for free DOX to 615 nm for conjugated DOX in the synthesized Fe₃O₄@DOX. Both free DOX and Fe₃O₄@DOX show strong cytotoxicity to legumain overexpressing PLC through apoptosis. Similarly, Fe₃O₄@DOX and DOX equally reduced tumor volume and induced cell apoptosis in tumor tissues, while the former significantly maintained body weight and extended the life of nude mice, therefore serving as a promising nanocarrier for liver cancer treatment.