<p>Grouting serves as a critical method for anti-seepage reinforcement in fractured rock masses. Model testing is a primary approach to investigate grouting mechanisms and laws in fractured rock masses. To this end, a self-designed visualized experimental system for single-fracture grouting was developed, and experimental research on the coupled laws of grout seepage diffusion and fracture deformation during the entire grouting process was conducted. The entire process of grout seepage diffusion, solidification, and fracture deformation in a single fracture was observed. Systematic analyses were performed on grout diffusion patterns, grout pressure variations, fracture deformation laws, and grout consolidation bodies. Experimental results were validated and theoretically explored using fracture deformation control equations. The study shows that: (1) During the grouting stage, the relationship between fracture aperture and grout pressure aligns well with the grout-rock coupling interaction pattern, exhibiting a positive linear correlation; (2) After grouting cessation, a distinct secondary migration phenomenon occurs, with the grout diffusion range increasing by 61.82% compared to the time of cessation. In this stage, the primary factor controlling fracture deformation is the variation in the volume of the liquid phase within the fracture space; (3) Based on fracture deformation magnitude, inter-fissure pressure changes, and grout diffusion phenomena, the fracture grouting process can be divided into three stages: grouting, post-grouting secondary migration, and grout flocculation-solidification; (4) Throughout the process, the movement of grout particles plays a significant role and exhibits a certain degree of coupling effects with other factors. The findings of this experiment hold reference significance for studying the dynamic evolution characteristics of grout during the entire seepage and diffusion process, as well as the coupling interaction patterns between grout and fracture deformation.</p>