The mechanical properties of reinforced body with double unbonded prestressed reinforcements are affected by the pre-tension applied on it. In scale model tests, steel shot was adopted to simulate the intensity of cohesionless fill and the stress state of the reinforced body. The distribution of deformation in the reinforced body and the soil pressure on the back of slab were obtained through applying pre-tension on unbonded prestressed reinforcement and heaped load at the top of reinforced body step by step. The test results were compared with those of common reinforced body. Results revealed that the settlement on the top of the reinforced body in the presence of pre-tension was smaller than that of common reinforced body in the absence of pre-tension. The increment of pre-tension reduced the horizontal deformation of slab and affected the settlement on the top of the reinforced body, which depends on the position of unbonded prestressed reinforcement. Moreover, the horizontal deformation of slab and vertical deformation of the prestressed reinforced body changed little under heaped load. When applying pre-tension, there is almost no interaction between the reinforcements.