In this paper, molecular modeling and optimization for the naphtha catalytic reforming process is studied. The catalytic reforming process is for producing high octane number gasoline by reforming reactions in three sequencing fixed bed reactors. Feed naphtha coming from an atmospheric distillation unit consisted of molecules from C5 to C10 including paraffin, iso-paraffin, naphthene, and aromatic. The molecular reaction network consisted of paraffin cracking, naphthene side-chain cracking, aromatic side-chain cracking, ring opening, ring closure, paraffin isomerization, dehydrogenation, and hydrogenation. A molecular model for catalytic reforming was built. On the basis of the simulation model, a process optimization was performed for feed temperature and pressure under constraints such as benzene content, aromatic content, and RON (Research Octane Number) limitations. High RON was contrasted to low benzene and aromatic content requirements. By optimizing and controlling the reaction pathway, we can obtain a final product with the highest profit and appropriate benzene and aromatic contents and RON value. This example shows significant benefits from applying molecular modeling to optimization in the process level. Since gasoline production is related to many different processes such as reforming, FCC, isomerization, alkylation, and so on, more benefits can be obtained by applying molecular modeling to plant-wide optimization.