The clay shock method is introduced as an auxiliary method for controlling strata displacement in shield tunnel crossing projects near existing buildings. The permeability and diffusion of clay shock in the strata have a significant impact on the filling effect of the circumferential gap between the shield shell and the strata. The rheological properties of clay shock and its microscopic composition have a significant impact on its fluidity. This article studies the changes in slurry performance based on the analysis of the rheological properties and microscopic components of the slurry. Further combining the bingham fluid sand seepage formula and numerical calculation model, the specific impact of slurry performance on seepage effect was analyzed. The reliability and rationality of the numerical model were verified. The results show that: (1) The nonlinear regression coefficients of each group of clay shock slurry samples under bingham constitutive model are greater than 0.95, and the plastic viscosity and yield strength will increase with the decrease of water-powder ratio. (2) The main components of clay shock slurry are quartz, albite, illite and orthoclase. With the increase of water-powder ratio, hydration product albite increases, while the content of illite decreases. (3) The clay shock slurry will fill the circumferential gap in about 25 seconds, and then undergo infiltration and diffusion into the stratum. The increase in the volume fraction of the slurry in the formation decreases over time until the increase rate drops to 0. (4) As the water-powder ratio increases, the permeability coefficient of the formation increases, and the grouting pressure increases, the clay shock slurry will increase the diffusion distance of the stratum. The average error between the theoretical and numerical value under various operating conditions should be within 10%.