This paper describered a simple and versatile method to prepare carbon nanotubes (CNTs)/magnetite nanocomposites (MNPs) by covalent interaction. The structure and morphology of CNTs/MNPs nanocomposites were characterized by FT-IR, XRD and TEM. The magnetic properties and electrical properties were measured by vibrating sample magnetometer (VSM) and LCR meter. The results showed that MNPs were effectively attached onto the surface of CNTs and CNTs/MNPs nanocomposites exhibited outstanding electrical and magnetic response. The saturation magnetization and electrical conductivity can reach ~ 40emu/g and 3.82×10-1S•cm-1, respectively. These one-dimensional electromagnetic nanostructures may find a wide range of applications in nanoelectronics, magnetic data storage, magnetically guided drug delivery and biosensors.