Stirred tanks are widely used in many industrial processes. The quality of mixing process generated by the impellers can be determined using either experimental and simulation methods by using computational fluid dynamics (CFD) or both methods.Numerous models and solution techniques have been developed over the years to help describe a wide variety of fluid motion. In this study computational fluid dynamics were performed to examine the flow characteristics of Mixing processes can be based on a number of mechanisms, from agitation to sparging to static flow manipulation. Agitation in a stirred tank is one of the most common operations, yet presents one of the greatest challenges in the area of computer simulationsix flat blades Rushton turbine type in cases of one impeller only and two impellers in baffled tank., Making an optimization design for mixing tank. The Multiple Reference Frame (MRF) approach was used to simulate the impeller rotation. ANSYS Fluent 15.07 solver and the RNG turbulence model Were used.