The PMN/EP composites were prepared by resin casting method from PMN powder pretreated with silane coupling agent KH-550. The microstructure of the PMN/EP composite was observed by SEM, the damping property and dielectric property of the composite were investigated by dynamic mechanical analyzer and impedance analyzer respectively. In the composite prepared with PMN powder pretreated by 1.5% silane coupling agent, much epoxy resin fragment is attached in the surface of PMN particles. When the silane coupling agent concentration is 1.5%, the composite shows the best damping property. Dielectric analyses suggest that the dielectric constant of the PMN/EP composite decreases with the increase of silane coupling agent content, however the dielectric loss increases with the increase of silane coupling agent content.