The invention discloses a preparation method of a ferroferric oxide/ titanium dioxide magnetic biological activity coating. The preparation method comprises the steps of firstly, utilizing a solvent-thermal method, adopting ethylene glycol as a solvent, adopting 1,6-hexamethylenediamine, ferric trichloride hexahydrate and anhydrous sodium acetate as solutes, reacting in a reaction kettle, and obtaining water-soluble aminated ferroferric oxide magnetic nanoparticles after finishing reaction; secondly, adopting a microplasma oxidation method, adopting water as a solvent, adopting the water-soluble aminated ferroferric oxide magnetic nanoparticles, calcium salt, phosphor salt and weak acid as solutes, and forming an electrolyte solution; and adopting a titanium/ titanium alloy sample as an anode and stainless steel as a cathode, adopting a pulse power supply for carrying out microplasma oxidation treatment on the titanium/ titanium alloy sample, and after finishing reaction, generating the ferroferric oxide/ titanium dioxide magnetic biological activity coating on a surface layer of the titanium/ titanium alloy sample. The magnetic material can respond to an external magnetic field, a magnetocaloric effect is produced through the external alternating magnetic field so as to heat up a focus area, and tumor cells are killed, so that the function of bone cancer magnetic hyperthermia is realized.