The composites with high permittivity and low dielectric loss were obtained. The fillers were the core@shell structure of the self-passivated aluminum (Al) particles (denoted as Al@Al2O3). The Al2O3 interface between Al and polymer matrix played important role in tailored dielectric properties of composite. The transmission electron microscopy (TEM) indicated that the Al2O3 shell was 2.7 nm. The self-passivated Al/polystrene (PS) composite displayed that the permittivity almost independed on frequency in wide range (102-107 Hz) and retained high-steady level, which is 27.4 times higher than that of a neat PS. On the other hand, the effect of size ratio value of core/shell in core@shell structure filler on dielectric performance of self-passivated Al/PS composites was also explained. The insulating oxide layer (Al2O3) restricts the electron transfer between Al particles. Moreover, the self-passivated Al/PS composites exhibited very steady dielectric performance at the wide temperature range (－60 ~60 °C). The composites have potential application in dielectric materials.