Abstract: With the rapid development of high-performance and lightweight electronic devices, the problem of electromagnetic interference shielding (EMI) has become increasingly prominent, and electromagnetic shielding materials have emerged as the times require. In this study, fused deposition modeling (FDM) 3D printing technology was used to prepare continuous carbon fiber-reinforced polyvinylidene fluoride (PVDF)-based electromagnetic shielding composites. Firstly, the printing parameters were systematically regulated by the control variable method to determine the optimal printing process parameters for the mechanical properties of the composites. Subsequently, the PVDF matrix used for printing was modified by adding magnetic component ferroferric oxide (Fe₃O₄) and conductive component multi-walled carbon nanotubes (MWCNTs) to enhance the electromagnetic shielding effectiveness of the devices and explore the shielding effect of the two materials in the electromagnetic field. In addition, the overall electromagnetic shielding performance of the composites was further improved by optimizing the printing paths (grid crossing, concentric circles, etc.). The experimental results show that the composite parts with a thickness of about 2 mm can achieve an electromagnetic shielding effectiveness (SE) of more than 33.4 dB in the X-band, exhibiting excellent shielding performance, which provides the possibility for the lightweight and customized processing of electromagnetic shielding materials.