Abstract: It has been proved that pulsed magnetic fields can significantly improve the electromagnetic shielding performance of composite materials by inducing the orientation of nanoparticles in the matrix. However, the influence of pulsed magnetic field amplitude on the electromagnetic shielding performance of composite materials is still unclear. Therefore, a pulsed magnetic field with a pulse width of 10 μs and a frequency of 50 Hz was used to induce the oriented arrangement of flaky carbonyl iron (FCI) in polydimethylsiloxane (PDMS). The influence of magnetic field amplitude (0~0.7 T) on the electromagnetic shielding performance of composite materials was studied. The orientation and arrangement of the nanoparticles were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the pulsed magnetic field can effectively control the orientation and arrangement of carbonyl iron, form a conductive network structure, improve the conductivity of the composite, and finally significantly improve the electromagnetic shielding performance of the oriented composite. The shielding effect of the pulsed magnetic field on the composite can reach 27%, and the highest shielding efficiency is 15.36 dB. The agreement between theoretical analysis and experimental results confirms the effectiveness of a microsecond pulsed magnetic field in improving the electromagnetic shielding performance of composite materials. The high-performance flexible electromagnetic shielding composite prepared in this study has the potential to be applied in advanced electronic devices.