The present invention relates to ceria nanocomposite, pharmaceutical composition comprising the ceria nanocomposite, and method for preparing same. More particularly, the present invention is directed to a ceria nanocomposite comprising a ceria nanoparticle, wherein the ceria nanoparticle is encapsulated with a surfactant and the surfactant is encapsulated with polyethylene glycol-phospholipid, pharmaceutical composition for preventing or treating ischemic stroke comprising thereof and method for preparing the same.