A lens structure and a 3D display device having the same are provided. The lens structure has unit regions. Each unit region includes upper and lower substrates, an anisotropic birefringence medium, center electrodes, edge electrodes and at least one set of side electrodes. The upper and the lower substrates are disposed oppositely to each other. The anisotropic birefringence medium is located between the upper and lower substrates. The center electrodes, the edge electrodes and the at least one set of side electrodes are located on the upper and lower substrates. The edge electrodes are disposed corresponding to the center electrodes. The at least one set of side electrodes are disposed between the center electrodes and the edge electrodes. An electric field distribution is formed between the center electrodes, the edge electrodes and the at least one set of side electrodes, so that the anisotropic birefringence medium constitutes a Fresnel lens.