This paper presents an edge-based smoothed finite element method (ES-FEM) for evaluating human exposure under extremely low frequency (ELF) electric fields. The problem domain is first discretized into a set of four-nodes tetrahedral elements, and linear shape functions are employed to interpolate the field variables. Then, the smoothing domains are further formed with respect to the edges of element. In order to improve the accuracy of lower order interpolation, a gradient smoothing technique (GST) is introduced to perform the electric potential gradient smoothing operation over each smoothing domain. Based on the generalized smoothed Galerkin weakform, the discretized system equations are finally obtained. Numerical examples, including both benchmark and practical complex cases, demonstrate that the present method possesses the following interesting properties in human exposure simulation under ELF electric fields: (1) super accuracy and faster convergence rate; (2) higher computational efficiency; (3) more immune to mesh distortion.