Abstract: The basic concept and experimental apparatus of combinatorial catalysis are summarized, and its applications to the R&D of petrochemical catalysts for such reactions as selective oxidation of propylene to propylene oxide, side-chain alkylation of toluene and methanol to styrene, butadiene to tetrahydrofuran and oxidative dehydrogenation of ethane/propane to ethylene/propylene are introduced. Combinatorial catalysis would be most likely an effective way to find new catalytic materials and novel catalytic processes in the future.