This paper aims to solve the poor toughness, small compressibility of high-water material. Based on the analysis of the failure characteristics of the backfilling body, the roadside backfilling body was divided into the yieldlayer and the support layer by the "yielding resistance" supporting mechanism. Orthogonal method was adopted to improve the high-water material performance, and the microstructure of the consolidated material before and after modification was compared. At the same time, simulation tests were conducted to obtain the optimal supporting conditions and material mechanical properties of backfilling body under lateral constraint conditions. The results showed that foaming agents and fibers had no effect on the formation of ettringite and other hydration products.The 28 days strength of the improved support layer consolidate body reached 12.18 MPa and the expansion rate of the yielding layer was 9.60%.The surface displacement of the optimal support combination under lateral constraint was 3.65%. The following industrial test indicated that the lateral surface displacement of filling body was only 229 mm, and the roof subsidence was controlled at about 216 mm. The high water material after modification can well meet the requirements of gob-side entry retaining.