<p>The computational fluid dynamics (CFD) and kinetic-based method of moments coupled approach is adopted to simulate the aqueous suspension polymerization process of Acrylonitrile (AN) in a stirred tank reactor. The accuracy of the CFD model for the polyacrylonitrile (PAN) polymerization reactor was validated by comparing simulation results with actual industrial production data. This revealed the distribution patterns of the velocity field, concentration field, temperature field and polymerization products within the PAN polymerization reactor. The effects of key reactor parameters – namely impeller diameter, bottom impeller clearance (height above the vessel base), and inter-impeller spacing – on the component concentration distribution inside the reactor and the polydispersity index (PDI) of the polymerization product were investigated. The simulation results identified optimized value ranges for the main structural parameters of the stirred tank. This work could offer valuable insights and a reference for the intensification of the industrial polymerization process and the design of such reactors.</p>