1-lsopropyl-4-methylbicyclo[2,2,2]oct-5-ene-2,3-dicarboxylic anhydride(TMA) was prepared via isomerization of terpineol-products followed by Diels-Alder reaction with maleic anhydride in the presence of phosphate catalysis. The optimum conditions were found by orthogonal tests to be as follows: reaction temperature 155 ℃, catalyst mass fraction of 1.5%, catalysts mass fraction of 0.08%, n ( by-product of principal component): n (maleic anhydride) = 2.2:1, and reaction time of 2 hours.The yield of TMA amounted to 86.2% .The structure of the TMA was analyzed and characterized by IR, NMR and MS.