Abstract: The aluminium powder(Al) is coated with silicon dioxide (SiO2) to prepare SiO2 @ Al by sol-gel method, and the SiO2@Al-KH550 is getted by organic modification using silane coupling agent KH550. The coating and the treatment effect are characterized by FT-IT, the corrosion resistance and hydrophobicity are verified by the corrosion efficiency experiment and static water contact angle experiments, and the microstructure is tested by SEM analysis. SiO2@Al-KH550/EP composite materials are prepared by casting method. Dielectric performance tests show that when the content of SiO2@Al-KH550 reaching 35%wt, the dielectric constant reaches 30, 6 times of pure epoxy resin, and the dielectric loss reaches 0.065, a new idea of the preparation of metal particles/epoxy resin dielectric composite materials is provided.