To analyze the rheological characteristics and applicability of organic-inorganic composite grouting materials in high-temperature environments, a two-component water glass-modified polyurethane grouting material is prepared, with water glass, glycerol, and catalyst as Component A, and isocyanate, plasticizer, and flame retardant as Component B. First, the curing time and viscosity of the slurry under different temperature conditions are tested; meanwhile, the influence of the two-component mass ratio and temperature on the curing time of the new grouting material is analyzed, the time-varying pattern of slurry viscosity and its temperature response characteristics are studied. Then, the rheological constitutive equation of the water glass-modified polyurethane slurry is established. The solidification mechanism of the slurry is analyzed based on the chemical reaction principle of the material and microscopic experiments. The results demonstrate the following: (1) During the curing process, the viscosity of slurry increases exponentially with time, and the increase in temperature accelerates the reaction process of the slurry, thus establishing a unified rheological constitutive equation for the water glass-modified polyurethane slurry considering both time and temperature. (2) Under different temperatures, the curing time of the water glass-modified polyurethane slurry shows a similar trend with the change of the two-component mass ratio. Considering the effects of mass ratio and temperature, a fitting equation for the slurry curing time is derived. (3) The free water in the water glass reacts with isocyanate to release CO₂, and Na₂SiO₃ absorbs CO₂ to form sodium carbonate (Na₂CO₃) and orthosilicic acid. The orthosilicic acid further undergoes dehydration and polycondensation to form SiO₂ or silicate deposition phases, which together with the polyurea/polyurethane organic matrix constitutes an organicinorganic composite structure.