The purpose of this study was to investigate the influence of particle size of pigments for Soy water-based inks on the pigment dispersion quality. The information can be used to obtain a standard laboratory condition at which a wide range of pigments may be dispersed to formulate water-based flexographic packaging inks. The influence of pigment concentration and shear forces on the pigment dispersion were also studied. Also, it is to provide basic grounds for understanding of the pigment's particle size characterization for soy water-based ink with the use of three different types of laboratory scale pigment dispersion and milling equipment used for grinding the pigments and ink formulation components to achieve the desired particle size for the flexographic packaging ink formulation. The procedure consisted of dispersing the pigment using a three different types of laboratory mills at various milling times with two different rotation speeds and measuring the particle size and particle size distribution of the milled samples. This pigment was dispersed at standard laboratory condition with different pigment concentrations.