Magnetic hyperthermia therapy(MHT)is able to ablate tumors using an alternating magnetic field(AMF)to heat up magnetocaloric agents(e.g.magnetic nanoparticles)administered into the tumors.For clinical applications,there is still a demand to find new magnetocaloric agents with strong AMF-induced heating performance and excellent biocompatibility.As a kind of biocompatible and biodegradable material,magnesium(Mg)and its alloys have been extensively used in the clinic as an implant metal.Herein,we discovered that the eddy thermal effect of the magnesium alloy(MgA)could be employed for MHT to effectively ablate tumors.Under low-field-intensity AMFs,MgA rods could be rapidly heated,resulting in a temperature increase in nearby tissues.Such AMF-induced eddy thermal heating of MgA could not only be used to kill tumor cells in vitro,but also be employed for effective and accurate ablation of tumors in vivo.In addition to killing tumors in mice,we further demonstrated that VX2 tumors of much larger sizes growing in rabbits after implantation of MgA rods could also be eliminated after exposure to an AMF,illustrating the ability of MgA-based MHT to kill large-sized tumors.Moreover,the implanted MgA rods showed excellent biocompatibility and～20％of their mass was degraded within three months.Our work thus discovered for the first time that non-magnetic biodegradable MgA,an extensively used implant metal in clinic,could be used for effective magnetic thermal ablation of tumors under a low-field-intensity AMF.Such a strategy could be readily translated into clinical use.