Abstract: The carbon nanotubes (CNTs)/epoxy composites were fabricated via 3D-printing technology and dip coating method. Superior shielding effectiveness of 39.2 dB and conductivity of 35 S/m (2 mm of sample thickness) were achieved with only 2.86vol% CNTs loading in CNTs/epoxy composites. The absorption electromagnetic interference shielding effectiveness accounts for 98% of the total electromagnetic interference shielding effectiveness, confirming that absorption is the primary shielding mechanism rather than reflection in CNTs/epoxy composites, certifying the proposed model. It is worth noting that the flexural properties of CNTs/epoxy composites are better than those of the original 3D-printed epoxy. The research provides creative new ideas and methods for the preparation of polymer matrix composites with excellent electromagnetic shielding performance.