Online pulse-reaction chromatography, MS transient response technique and fixed bed reaction apparatus were used to investigate the cracking of thiophene and alkyl-thiophene species. Thiophene cracks over the USY zeolite to propylene, butane, butene and H2S. Furthermore, 2-methyl-thiophene, 3-methyl-thiophene, di-methyl-thiophene, tri-methyl-thiophene and benzothiophene are formed, but cracking desulfurization is the dominant reaction. Compared to thiophene, alkyl-thiophene species in gasoline are easier to desulfurize via cracking over the specially prepared sulfur removal catalyst with the USY zeolite as the cracking component, and the conversion increases with the alkyl carbon number of alkyl-thiophene. Cracking and hydrogen transfer are two important elementary reaction steps for thiophene and alkyl-thiophene species desulfurization via cracking. Higher temperature favors the former, while lower does the latter. The contradiction leads to about 400 degreesC to be the optimal temperature for thiophene and alkyl-thiophene species to desulfurize via cracking.