To understand the role of phosphate ester dispersant, we investigated the rheology of a BaTiO 3 slurry. For the model case, a coarse-grain molecular dynamics (CGMD) simulation was performed with the butyral polymer didodecyl hydrogen phosphate (DHP) in the toluene/ethanol solvent. By systematically analyzing the effect of DHP from an atomic-scale first principle and from all-atom MD to microscale CGMD simulation, we investigated how the adsorption of a DHP dispersant on a BaTiO 3 surface affects the microstructure rheology of a BaTiO 3 slurry. The first-principle and all-atom MD simulation suggests that DHP molecules prefer to locate near the BaTiO 3 surface. CGMD simulation shows a reduction in viscosity with an increase in dispersants, suggesting that the dispersant population near the BaTiO 3 surface plays a key role in controlling the rheology of the BaTiO 3 slurry. In this study, we propose an approach for understanding the BaTiO 3 slurry with molecular-level simulations, which would be a useful tool for efficient optimization of slurry preparation.