Abstract: The adsorption of binary and ternary mixtures of thiophene, benzene, and n-hexane in MFI and MOR zeolites was simulated by using the Monte Carlo technique in grand canonical ensemble. The binary simulation results showed that thiophene molecules took precedence over benzene molecules to occupy the intersection sites in MFI. When the pressure was raised, the loading of benzene increased gradually, whereas the loading of thiophene reached a plateau. Benzene molecules were pushed to the zig-zag or straight channels by thiophene molecules. The binary system in MFI conformed with competition model by Clark et al. However, there were no distinct preferred sites for adsorption of thiophene and benzene on MOR zeolite, and the systems complied with volume filling model. The ternary simulation results showed that the adsorptive amount of n-hexane was the greatest, while the thiophene and benzene are adsorbed very little in MFI zeolite. The adsorptive amount of thiophene was the greatest, while the n-hexane and benzene were adsorbed very little in MOR zeolite. For the molecules with bulker size, they could occupy only the main channel in MOR. A little amount of n-hexane had a stronger effect on the adsorption of benzene than that of thiophene.