Abstract: A model of fluid-particles interaction and Van der Waals force is developed based on discrete element program YADE to analyse the packing state of slurry particles during the initial constant rate period. The packing state is analyzed from partical diameter ratio and Van der Waals forces. The analysis results show that the Van der Waals force has a great influence on the velocity of the slurry membrane formation and the spatial force chain structure, resulting in quantitative change of the packing ratio. The partical diameter ratio is the determinant of the slurry membrane state. The spatial distribution and connections of the force chain structure reflecting the slurry particles packing in soil have features of continuity and unidirectionality. Seepage unidirectionality is an important form of the packing unidirectionality, and it is validated by a set of sand-bentonite mixture falling head permeability tests. Larger Van der Waals force can make faster the slurry membrane formation on the soil surface, which provides a theoretical support to optimize slurry mixing ratio by raising fluid Hamaker constants through the theoretical and experimental methods. Owing to complex formation mechanism of the slurry membrane and many influence factors, it is unable to reveal formation process of the slurry membrane clearly. And a problem of the slurry membrane formation transformation from the constant-speed stage into the constant-pressure stage will be an research emphasis in the future.