Abstract: Preparation of methotrexate microsphere ( MTX-ms) by emulsion-freezing technique was introduced and the experimental results proved that MTX entrapped in the microspheres exhibited good stabilties towards temperature, cobalt- 60 radiation and light. The dissolution and inflation rate of the microspheres in pH 7.4 buffer solution at different times measured by Coulter counter was presented. Antitumor activity of MTX-ms after hepatic arterial embolization was examined in a model of liver tumor in Wistar rats. The group of rats treated with MTX-ms showed a rather significant reduction in tumor growth and more extented tumor necrosis as compared with the other groups, e. g. normal saline solution, MTX solution, placebo gelatin- ms and the results demonstrate that the effect of arterial chemoembolization used by MTX-ms is superior to that of the groups either using arterial chemotherapy or arterial embolization alone in treating rat liver cancer.