3D Equivalent magnetic Circuit Network Method (EMCNM) is comparatively the easy way that analyzes 3D models of Electric Machine by using permeance as a distributive magnetic circuit parameter under the existing magnetic equivalent circuit method and Numerical Method. The existing 3D EMCNM could not correctly describe the shape of an analysis target when using rectangular shape element or fan shape element, so it made errors when calculating permeance. Therefore, this paper proposes the trapezoidal element contained rectangular element, fan-shape element, and quadrilateral element to express a shape. The proposed method in this research was confirmed as a useful and an accurate method through comparing with the analysis result of SRM model that is sufficiently guaranteed by 2D-Analysis.