Abstract: It is an important method to study the deformation and stress characteristics of discrete media such as geo- chemistry from the perspective of micromechanics. Based on the theory of micromechanics,PFC2D numerical simula- tion test technology is used. The development of the grouting process such as the distribution of tensile stress field,the deformation movement of soil particles and their coupling with slurry can be revealed from a microscopic point of view. It provides a new way for the study of grouting reinforcement of weak soils,weathered rocks and broken belts. In this paper,based on the principle of fluid-solid coupling,the numerical simulation program of PFC2D particle flow is used to define the flow equation and the pressure equation of the flow domain. The diffusion process,morphology and parti- cle displacement of the slurry during the grouting process were numerically simulated. By adjusting Hist,n_bond,s_ bond,and measure parameters in the PFC command flow,the particle displacement changes are tracked,and the diffu- sion laws and formation porosity changes in different depths are revealed. The numerical results show that the effect of grouting pressure on the formation structure is very significant,the cracking effect of the increase of adhesion strength is gradually reduced,and the porosity increases with the increase of grouting pressure. The ElastoPlastic theory based on Mohr-Colomb criterion is used to deduce the stress field of soil around the borehole. It is pointed out that the me- chanical mechanism of circular pull radial pressure is the fundamental reason for the occurrence of splitting grouting mode of action. The increase of viscosity of slurry is beneficial to improve the grouting effect of split-compacted grou- ting, and the increase of friction coefficient has little effect on grouting effect. The experimental results show that PFC2D simulation grouting process is feasible.