Particles concentration distribution in a stirred tank with pitched blade turbine was investigated using computational fluid dynamics. The effect of the pumping mode on the turbulent flow and particles concentration distribution was studied. The turbulent solid-liquid flow in a stirred tank was simulated using a two-fluid model with standard k-ε turbulence model. The multiple reference frames approach was used to simulate impeller rotation. Results show that different pumping modes create different flow field which decide the characteristics of the mixing quality. A further detailed discussion about particles mixing at the bottom of the stirred tank was made. The computational model and the predicted results discussed here would be useful for understanding the solid-liquid mixing process.