Computational fluid dynamics simulation is an increasingly useful tool in the analysis and design of stirred tank.To understand and improve mixing performance in the eccentric air jet-stirred reactor with double impeller system, it is necessary to simulate the flow field structure and its movement.The present work was focused on designing eccentric air jet-stirred system for such a process using Fluent (V.6.3.26) and its preprocessor Mixsim (V.2.1.10).Mixing performance and flow field structure were simulated at various operation parameters.It showed that eccentric air jet could enhance the mixing performance by breaking the symmetry of flow field.