The hydrophobic bifunctional mesoporous of palygorskite solid acid was prepared by using H2O2 to oxidize the chemical palygoriskite, which is modified by grafting 3- mercaptopropyl trimethoxysilane and four kinds of silane coupling agent different carbon number. The samples were characterized by IR, XRD, SEM, BET, NH3-TPDand elemental analysis. The catalytic activity of solid acid was tested for the esterification of trimellitic anhydride with 2-ethyl hexanol. The experimental results showed that the catalytic activity of palygorskite solid acid was increased and amount of catalysts was decrased by hydrophobic hydrocarbon chain leading into. The esterification yield is 94.81% under the conditions： the molar ratio of trimellitic anhydride to 2-ethylhexyl alcohol is 1:4.5, the weight of catalyst is 1.2％ of total weight(0.12 g), the reaction time is 6 h and the oil bath temperature is at 210℃．