The grouting reinforcement strength of fracture surface is closely related to the microscopic behavior of slurry-rock interface. In this work, the spreading and penetration dynamics of nanosilica sol (NSS) droplets on granite, sandstone, and marble which cover the main types of rocks in nature were studied by experiments and numerical simulations. The control experiments were carried out by changing NSS and rock into distilled water and impermeable steel. The results show that the spreading behavior of granite and sandstone are similar because they are both porous rocks with similar mineral compositions. Based on the experimental data, two new scaling laws describing the maximum spreading factor as a function of the Reynolds number and the Weber number were proposed. The numerical models are validated against experimental data at the same condition. Following that, a parametric study is undertaken at various velocities, droplet initial diameters, equilibrium contact angles, porosity, and roughness. As the contact angle varies from 30° to 150°, the maximum spreading factor has a decrease of 49.7%, while the dimensionless penetration depth increases after decreasing. When the porosity ranges from 0.2 to 0.4, the dimensionless penetration depth has a significant increase of 138.7%. Besides, the dimensionless penetration depth increases after decreasing as the roughness gets higher. The results also show that the penetration depth has a negative correlation with the maximum spreading factor which reveals that there is a competitive mechanism of spreading and penetration. [ABSTRACT FROM AUTHOR]