Abstract: Two-dimensional graphene (G) nanosheets have a significant enhan cement effect on cement-based materials, but generally G is distributed haptically in cement-based materials. In order to better exert the strengthening effect of G, the magnetic nanocomposite Fe₃O₄@RGO (MGO) was prepared by one-step co-precipitation method by adhering Fe₃O₄ nanoparticles to thermal-reduced graphene oxide (RGO) nanosheets. By applying an external magnetic field (MF), the MGO nanosheets with different contents were arranged in a certain direction in the cement paste. The compressive strength of the hardened cement paste perpendicular and parallel to the magnetic field was tested respectively. The results show that the compressive strength of the cement paste mixed with different amounts of MGO in the direction parallel to the magnetic field is greater than that perpendicular to the magnetic field; when the content of MGO is 0.1%, the compressive strength of the section parallel to the magnetic field is 12.20% higher than that perpendicular to the magnetic field. The results indicated that the MGO nanosheets were oriented after induction by magnetic field, and the hydration products of cement grew in a regular arrangement parallel to the magnetic field. This study provides an effective way to achieve higher strength cement-based materials for specific applications by regulating the orientation of graphene nanosheets induced by an external magnetic field.