Abstract: In order to study the dynamic change process of permeability velocity during soil seepage process, the permeability dynamics test device was used to monitor the change trend of permeability coefficient under different water heads. At the same time, the CFD-DEM numerical simulation analysis method combined with the API secondary development function was used to analyze the liquid bridge force caused by the increase of water content between the particles. The permeability coefficient was decreased with time under different water heads. The soil model of common particle accumulation was difficult to analyze the change of permeability coefficient during the seepage process. After the API application, the particle adhesion under the action of the liquid bridge force was enhanced. And the same change process of permeability coefficient was found by using the API function as in the experiment. Therefore, liquid bridge force was one of influencing factors which caused a sudden decrease in the permeability coefficient during the seepage process.