The rheological properties of the material during the gelation process of fluid catalytic cracking (FCC) catalyst are complex, exhibiting pseudoplastic fluid characteristics with shear-thinning behavior. In order to enhance the mixing efficiency in the FCC catalyst gelation agitated tank, the computational fluid dynamics (CFD) numerical simulation method was used in conjunction with rheological characterization obtained by a rotational rheometer. This method was employed to investigate the influence of different impeller configurations on the mixing effect of high-viscosity, variable-viscosity systems. Due to the difference of rheological properties in different steps of gel process, it needed to be discussed separately and strengthened. By comparing and contrasting the flow field distribution, shear rate distribution and viscosity distribution inside the kettle for different gelation processes, the most appropriate stirring device for each stage can be determined. Based on the design of a new type of folded blade propeller, the multi-layer combination propeller was used in order to achieve the uniform distribution of the flow field and shear rate within the gelation agitated tank. This reduced the high viscosity weak mixing zone in the tank and improved mixing efficiency. The marked grid method was employed to compare the mixing time under different combination structures. The results showed that the optimized multi-layer impeller combination can realize the mixing strengthening of the gelation process. In the mixing process of kaolin, the combined impeller of lower SBT+upper FBT was adopted. In the mixing process of FCC catalyst colloid, the combined impeller of lower SBT+middle FBT+upper PBT was used. Considering the requirements of industrial design, the combined impeller of lower SBT+middle PBT+upper PBT was adopted in industry. This ultimately resulted in a significant reduction in the mixing time required for gelation, which strongly supported energy saving and consumption reduction in factories.