EVA is an important high-performance resin material obtained by the copolymerization of ethylene and vinyl acetate. In the present study, a comprehensive computational fluid dynamics (CFD) model was established to study the EVA free radical copolymerization process. The polymerization kinetic model was combined with the CFD model. The EVA copolymerization reaction mechanism was verified by comparing the simulation results with the experimental results. Detailed information of the flow field inside the industrial EVA autoclave reactor was obtained. With the increase of the impeller speed, both the axial and radial flows inside the autoclave reactor were enhanced. The high impeller speed improved the fluid mixing and the homogeneity of temperature distribution. The increase of the impeller speed improved the initiator dispersion near the inlets, thereby increasing the efficiency of the initiator. The influence of operating conditions on monomer conversion and specific initiator consumption per 1% of the monomer reacted was investigated. The simulation results give deep insight into the free radical copolymerization process inside the autoclave reactor and supply the guidelines for developing an industrial autoclave reactor.