For conventional reinforced soil, the reinforcements are put horizontally in the soil. A new concept of soil reinforced with three-dimensional elements was proposed. In 3D reinforced soil, besides conventional horizontal reinforcements, some vertical and 3D reinforcements can also be laid in the soil. The triaxial tests on sand reinforced with 3D reinforcement were carried out. From the experimental results, the differences of stress-strain relationship and shear strength between horizontal reinforced sand and 3D reinforced one were analyzed. The experimental results show that 3D reinforcement not only increases its cohesion, the angle of internal friction has been increased greatly, especially with 3D elements on both sides. Based on experimental results, a retaining structure reinforced with 3D reinforcements was analyzed by the finite element method. The stress distribution and interaction between 3D elements and soil were studied. The plastic zone and stability analysis of the retaining structure reinforced with 3D reinforcements were investigated by finite element method by shear strength reduction technique.