Slurry diffusion is the key factor affecting the resistance reduction of pipe jacking grouting. Therefore, this paper establishes a three-dimensional numerical analysis model of pipe jacking, introduces a diffusion ring to simulate the slurry diffusion process during pipe jacking construction, modifies the friction coefficient according to the contact between the soil around the pipe and the segment, and studies the influence of the slurry diffusion process on the resistance reduction effect during pipe jacking construction. The calculated jacking friction is compared with the measured data to verify the reliability of the method proposed. The influence of the filtering effect on soil displacement and the influence of grouting diffusion-related parameters on soil displacement and jacking friction during pipe jacking construction are further studied. The results show that the surface subsidence is smaller when the filtration effect is considered; The stronger the attenuation of permeability coefficient caused by the filtration effect, the smaller the surface settlement and jacking friction resistance; The faster the slurry diffuses and the more complete the slurry jacket is, the better the resistance reduction effect of grouting during pipe jacking.