Abstract: Based on the theory of elasticity, the theoretical formulas are derived to calculate the horizontal additional stress (σ_H) in a new type prestressed embankment, and the diffusion laws of the additional stress from the slope surface to the inside of the embankment are revealed. Meanwhile, a 3D finite element model for a prestressed embankment is established to analyze the distribution of the horizontal additional stress in the prestressed embankment with different placement positions of the lateral pressure plate. The results show that: (1) The application condition of the theoretical formulas requires that the net spacing between the lateral pressure plate and the embankment shoulder should be more than 2.0 m. (2) In the region covered by the lateral pressure plate, the horizontal additional stress coefficient as well as its attenuation rate gradually decreases with the increase of the horizontal distance from the slope surface, and the distribution of σ_H gradually transits from a “raised abdomen” pattern to a relatively uniform “flat abdomen” one. (3) When the distance away from the lateral pressure plate is greater than 0.1 m, the additional stress coefficient of σ_H increases first and then decreases with the increasing horizontal distance, and the horizontal distance between the peak point and the slope surface increases as the epitaxial distance increases; (4) A continuous, stable and effective pressure-reinforced zone is likely to be formed when the spacing of the lateral pressure plate is properly designed, therefore, the stress state of the embankment soil and the overall service performance of the embankment can be improved. The research findings can provide theoretical bases and references for the design and promotion application of the prestressed embankments.