Traditional aerobic fermentation bioreactor agitators have all been of the same configuration and geometric dimensions, featuring multi-layer impellers such as three-layer six flat-blade, six arrow, and six curved-blade disk turbine impellers. They offer good shearing performance, but there is a clear division between layers, resulting in poor fluid circulation and hindering the overall mixing of the tank's fluid. By using a radial flow impeller at the bottom, which serves to shear and disperse gases, and axial flow impellers on the upper two layers for overall circulation, the contact area between gas and liquid is increased, and the bubble residence time is prolonged, achieving an efficient and energy-saving effect. This combination of different types and geometric dimensions of impellers installed on the same agitator shaft has been successfully tested in industries such as penicillin fermentation and citric acid fermentation, yielding significant energy-saving results. It is currently being widely promoted.