Abstract: Reaction performances of thiophene, 2-butylthiophene and benzothiophene were investigated by a FFB device under catalytic cracking conditions, and their reaction mechanisms and product sulfur distributions were discussed in detail. Results showed that the conversion of thiophene and benzothiophene were rather low (less than 20%), cracking to H2S was hard to happen in this case, thereby high selectivity of coke and liquid product was observed. As to 2-butylthiophene, it was quite active under catalytic cracking conditions, reactions including dealkylation, cracking of side chain and desulfurization took place mainly; in reaction product, sulfur distributed in gas reached 28%. With zeolite Y catalysts, good linear relationships existed in product yield-conversion, product sulfur distribution-conversion for thiophene species.