The invention discloses a superparamagnetic ferroferric oxide nano particle drug carrier. The rug carrier comprises superparamagnetic ferroferric oxide nano particles which are formed by polymerizing ferroferric oxide nanocrystal with the size being smaller than 10nm and can release ferrous ion under an acidic condition, an amorphous carbon layer which is coated on the surface of the superparamagnetic ferroferric oxide nano particles and can be resolved in an alkaline condition, silver nano particles coated on the surface of the carbon layer, and a silicon dioxide layer, with a porous structure, coated on the surface of the silver nano particle. The drug carrier can load natural drug artemisinin, overcome the disadvantage of poor water solubility of artemisinin, and convey more artemisinin to a tumor focus part through intravenous injection, after the artemisinin reaches the tumor part, as tumor cell is in acid microenvironment, the drug carrier releases ferrous ion in the cell, the ferrous ion cracks peroxide bridges in the tumor, free radical is produced, protein, DNA (deoxyribonucleic acid) and cell membrane of the tumor cell are destroyed, finally the tumor cell is killed, and the anti-tumor efficacy of artemisinin is improved.