The mixing process is applied in various contexts of geotechnical engineering, ranging from ground improvement to offshore mining. In this study, we apply the discrete element method (DEM) augmented by a lubrication model to simulate the underwater mixing process. Based on a set of calibrated material parameters with respect to an underwater mixing experiment, we vary the parameters to investigate their influences on the mechanical responses of the mixing process. The mechanical responses include the resultant torques on the blades, the normal forces on the wall and on the bottom, the effective masses mobilized by the mixing process. A newly proposed resistance index to mixing is also evaluated. A quantitative evaluation is conducted for the viscosity of fluid, the Young’s modulus, the Poisson’s ratio, the sliding and rolling friction parameters, the coefficient of restitution. Those material properties are classified into two catalogues, sensitive and insensitive, according to their influences. Analysis of the force (stress) chains has been conducted to reveal the differences between two catalogues of parameters. These findings can contribute to the designs of the mixing systems that work for different types of soils.