Isotropic Conductive Adhesives (ICAs) were prepared using epoxy resin as matrix, latent curing agent as hardener, and silver particles as the conducting filler. The effects of nano-fillers (SiO2 nano-particles and carbon nanotubes) on the conductivity, adhension strength and reliability of ICAs were investigated experimentally in this paper. The results showed that these two nano fillers can improve both the conductivity and adhesion strength of ICAs, which maybe attributed to the nano-particles forming physico-chemical bonds with epoxy resin. These physico-chemical bonds increase the contact area and then minish the interspace of Ag particles, so it reduces electrical resistance and enables a high current flow. And the increasing contact area will improve the contact strength between Ag particles and epoxy resin. Under the reliability testing with the high temperature and high humidity (85°C/85RH), the SiO2 nano-particles can improve the reliability of ICAs apparently, while carbon nanotubes can not. This is because insulating material can prevent silver migration.