The dispersion effect of particle aggregates has a direct impact on the comprehensive properties of com- posite materials.In order to reveal the dispersion mechanism and dynamic details of particle aggregates,a 3D dis- crete element program,Demix3D,which involves the van der Waals force among particulates,is developed to nu- merically simulate the deformation and dispersion process of aggregates in a simple shear flow field,and to further explore the mesostructure evolution of the aggregates in the dispersion process.The results show that complex force chain network caused by the interwining of strong and weak force chains form in the aggregates.In this network,the strong force chains mainly distribute in the interior and transfer the majority of the force from the flow field,while the weak force chains fully distribute in the network and transfer the minority of the force.Moreover,it is found that the dispersion mode of the particles is directly determined by the evolution of the force chain network,and that the fragments no longer disperse due to the close contact among the particles with strong force chains when the dispersion of the particles reaches its equilibrium.In addition,the effect of flow field intensity on the dispersion of the aggregates is analyzed according to the weighted average particle number of the fragments.