A method was developed for preparing silver/multi-wall carbon nanotubes (Ag/MWCNTs) composites after iodination of the MWCNTs. The MWCNTs were functionalized by ball milling in the presence of iodine, and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and thermogravimetric analysis (TG). The results show that the silver-nanoparticles (Ag-NPs) adhere better to the surface of the MWCNTs after iodination, which can improve the connection between the Ag-NPs and the MWCNTs. The hydroxyl (-OH) group stretching vibration is clearly enhanced, which activates the surface of the MWCNTs and increases the number of Ag⁺ nucleation sites on the surface of the MWCNTs. At temperatures lower than 260 °C, the mass loss of Ag/MWCNTs composite is less than that of MWCNTs. Finally, three silver-epoxy resin pastes were separately prepared, and the paste prepared using the Ag/MWCNTs composites has the lowest resistivity and the highest thermal conductivity.