By measuring the effective thermal conductivity, taking photos of the distribution of the nano-particles in the fluids and photos that reflect the interfacial phenomena between nano-particles and fluids, we try to explain the possible mechanism for heat conductive enhancement. By measuring the effective thermal conductivity, taking photos of the distribution of the nano-particles in the fluids and photos that reflect the interfacial phenomena between nano-particles and fluids, we try to explain the possible mechanism for heat conductive enhancement.