A thermal therapeutic reagent is provided. The thermal therapeutic reagent comprises a plurality of magnetic nanoparticles, a plurality of surfactants coating on the magnetic nanoparticles respectively, and a polar magnetic fluid for delivering the magnetic nanoparticles to a target site. Wherein, the magnetic nanoparticles are capable of being activated under a magnetic field applied at the target site. Another thermal therapeutic reagent comprising a non-polar magnetic fluid is also provided.
