Characterization results of Fourier transformed infrared spectrometer(FT-IR), thermogravimetry–differential thermal analysis TG–DTA, dynamic stability control (DSC), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) indicated that DOX loaded onto PEGylated superparamagnetic Mn0.6Zn0.4Gd0.04Fe1.96O4 (MNPs) was prepared successfully. DOX loading ration and release mechanism was analyzed; the result indicated that the DOX loading ration increased with initial charge DOX increasing, and DOX release was a Fickian diffusion mechanism, with 34.5% of DOX released in PBS solution at 43 °C within 168 h. Consequently, the MNPs@PEG may be a good targeted drug delivery system for tumor targeted and hyperthermia MNPs as therapeutic applications. [ABSTRACT FROM AUTHOR]