Abstract: Preparation of 2,6-dimethylnaphalene from toluene and 1,3-pentadiene is a new reaction process.Thermodynamic calculation on alkylation,cyclization,dehydrogenation and isomerization in this process was carried out via Thinh method.Standard molar enthalpies and equilibrium constants of foregoing reactions were obtained and optimum reaction conditions were investigated.The calculation results(indicate) that the preparation process is feasible,so as the coupling of dehydrogenation and isomerization(processes.)