Abstract: Affected by complex hydro-geological conditions, mine production is facing serious water hazards, with water inrush and sudden water accidents occurring from time to time. Advanced area grouting has become one of the main methods for preventing and controlling pressurized water hazards on coal seam floor. However, due to the heterogeneity of floor lithology and the complexity of geological structures such as faults and fractures, problems such as slurry leakage, seepage, and local undergrouting often occur during the grouting process, seriously affecting the grouting effect and the reliability of waterproof reinforcement. Based on the data of the grouting project in Xieqiao coal mine area, the vertical spatial distance between the fault and the grouting hole is defined as the fault distance. The simulation analysis of the slurry splitting and diffusion mechanism under different fault distances is carried out. The research focuses on the diffusion path, splitting mode, stress field changes, and micro-seismic monitoring response deviation of the slurry near the fault, revealing the influence law of different fault distances on the slurry splitting and diffusion characteristics, the direction of splitting stress, and the micro-seismic monitoring response deviation characteristics. The results show that under the combined action of in-situ stress fault grout pore pressure, the dynamic change of the maximum principal stress has an inducing effect on the deviation of grouting splitting diffusion direction to one side, and the influence range of this type has a limit value, which is affected by conditions such as fault trace length, dip angle, and ground stress; under the designed grouting engineering conditions, the influence distance of the fault on the grouting splitting diffusion reached 40 meters. Within this 40 m range, the presence of faults will cause the slurry to preferentially diffuse towards one side of the fault, significantly affecting its propagation path and splitting mode; the fault will affect the stress intensity factor K_IC of the grout splitting I-II composite crack before grouting, causing changes in the grouting direction and splitting pressure.