Abstarct: The properties of thermal conductivity of water baxsed Fe3O4/CuO nanofluid with respect to different parameters such as temperature and weight percent of forming nanoparticles were empirically investigated. The thermal conductivity was measured using hot wire method. According to the results, the thermal conductivity of the Fe3O4 nanofluid in the presence of different concentrations of CuO nanoparticles increases significantly. A linear relationship between increasing the concentrations of CuO nanoparticles and the growth of thermal conductivity of Fe3O4 nanofluid in the temperature range of 25 to 50 C was observed. The mixed Fe3O4/CuO nanofluid was selected and the role of external magnetic field effects with strength up to 0.2 T was determined on the thermal conductivity of the considered nanofluid with different basic parameters such as nanoparticle concentration and baxse fluid temperature. Thermal conductivity was measured using hot wire technique and the magnetic field applied uniformly to the nanofluid system with different situation of the field strength and weight percent of the both containing Fe3O4 and CuO nanoparticles. We have found that the thermal conductivity of the pure and the mixed Fe3O4 with CuO nanoparticle has significant enhancement at presence of the external magnetic field. However the rate of the thermal conductivity growth is strongly correlated with the magnetic field strength which is applied uniformly to the system.