Abstract: Small amount of multi-walled carbon nanotubes (MWCNTs) was mixed with certain content of WS₂ to fabricate a composite filler, then mixing which with ethylene propylene diene monomer (EPDM) to get the MWCNTs-WS₂/EPDM composites with different MWCNTs content. The composite samples were prepared by using a mixing process and the nonlinear conductivity, direct current dielectric breakdown strength and thermal conductivity of MWCNTs-WS₂/EPDM composites were investigated. The results show that with the help of WS₂, very small amount of MWCNTs enhances the nonlinear conductivity of MWCNTs-WS₂/EPDM composites obviously at 25℃, and the improvement is regularly by increasing the content of MWCNTs. Because of the excellent conductivity of MWCNTs and the electrical conduction positive temperature coefficient effect of itself, the nonlinear conductivity of MWCNTs-WS₂/EPDM composites decreases with the increasing of temperature. There is no nonlinear change for the conductivity of MWCNTs-WS₂/EPDM composites in increasing electric field at 80℃.The thermal conductivity of MWCNTs-WS₂/EPDM composites is improved obviously with the help of MWCNTs.