The SO42-/ZrO2 modified SEA mesoporous molecular sieves were prepared and characterized by XRD, N-2 adsorption, TG/DTG/DTA and IR pyridine chemisorption. The acidity of the molecular sieve was,greatly enhanced after modification, and IR pyridine chemisorption results revealed that Lewis acidity was dominant in these samples. The catalytic activities of the modified molecular sieves towards strong and medium strong acid catalyzed reactions were lower than those of bulk SO42-/ZrO2, but higher than those of Al-containing SEA molecular sieve from direct synthesis, whereas the activities of all these catalysts for weak acid catalyzed reaction were close to each other.