The invention relates to a modeling method for a heterogeneous azeotropic rectification solvent dehydrating tower of an industrial purified terephthalic acid (PTA) device. In the method, the vapor-liquid balance experimental data of an acetic acid, n-propyl acetate, water, p-xylene and methyl acetate quinary mixture system are associated and fitted with the binary interaction parameters of the quinary mixture system according to a thermodynamic property model; and according to the process data of the solvent dehydrating tower under the actual device design condition, a heterogeneous azeotropic rectification solvent dehydrating tower model of the industrial PTA device under the design condition is established, the accuracies of the thermodynamic model and parameters thereof of the quinary mixture system in a laboratory and a rectification tower mathematical steady model are verified, key parameters representing the separating property of the solvent dehydrating tower under the actual condition are acquired, the model is corrected and a process mechanism steady model capable of accurately describing the operating characteristics of the solvent dehydrating tower under the actual condition is established.