After long-term service in rich water environment, the mechanical properties of double liquid slurry are easily degraded by water corrosion. The variation law of the mechanical property attenuation of cement-sodium silicate double liquid slurry under the mixing ratio parameters and curing system was studied. Combined with various microscopic analysis methods, the mechanism of the mechanical property attenuation of cement-sodium silicate double liquid slurry under rich water environment was analyzed from the aspects of mineral composition and microstructure evolution. The results show that, curing in the low water content sand layer of 10%, 15% (mass fraction) are beneficial to the early strength development, but the strength gradually decreases in the later stage. The early strength of the test block in the 25% (mass fraction) high water content sand layer decreases by 23.5% compared to the 15% (mass fraction) water content sand layer, but the water corrosion effect is significantly weakened in the later stage, and the compressive strength at 220 d increases by 15% compared to 90 d. The standard curing conditions accelerate the deterioration of the mechanical properties of double liquid slurry, and the strength of the test block is 80.6% and 91.0% lower than that of water curing and sealed curing, respectively. The development of the mechanical properties is mainly controlled by hydration reaction and water corrosion. In the early stage, hydration reaction dominates, and in the later stage, water corrosion dominates. The development of the mechanical properties is essentially the effect of superposition of the two effects. The double liquid slurry material system is maintained in the rich water environment for a long time, and the hydration products on the outside of the matrix are constantly migrating and dissolving out. The outer layer of the test block forms a porous structure coating layer with a certain thickness, and becomes a migration channel for sodium ions, silicate ions and hydration products in the internal structure, which leads to continuous deterioration of the mechanical properties of the matrix.