Abstract: Due to the characteristics of 3D printing technology laminated manufacturing, the molded part has a layered structure inside, which has an impact on the electrical and mechanical properties of printed insulation used in the insulation field. The 3D printed insulation will show different properties from homogeneous insulation under high voltage because of the non-homogeneity of its layered structure. In order to clarify the changes in the electric field distribution of layered insulators compared to homogeneous insulators, two samples of nylon 12 with printing direction vertical and parallel to electric field direction were prepared. The relative dielectric constant, volume resistivity, and AC breakdown field strength of the two were mainly studied, and the relative dielectric constant and volume resistivity of different layers were derived from the series or parallel relationship of the layer. Experiments show that the sample with the layered structure which is vertical to electric field has the higher body breakdown strength. Furthermore, the electric field distribution of the layered insulator of the structure and the homogeneous insulator is studied. The results show that the maximum electric field strength of the layered insulator is higher than that of the homogeneous insulator due to the electric field distortion effect at the triple junction of the layered insulation surface, and the electric field distribution along the surface of the layered insulator is more nonuniform than the homogeneous insulator. The surface electric field distribution can be improved by changing the printing direction, but reduction in the body breakdown strength needs to be considered.