Abstract: Aroma components, expecial organo-sulfur compounds in four types of Chinese onion were extracted by SPME, and then identified by GC/MS. The results indicate that 3,4-dimethylthiophene is the major mono-thiosulphinates in Chinese spring onion, the highest content of which is in Zhangqiu spring onion, while the lowest content is in Xin108 onion; Dipropyl disulfide and methyl propyl disulfide are main di-thiosulphinates in the spring onions, the highest content of which is in Xin108 onion, compared to the lowest in Longyao spring onion. The tri-thiosulphinates is in contest of Dipropyl trisulfide, which is identified in all the onion, except Zhangqiu spring onion. It can conclude that different types of onion have different types of the major organo-sulfur compounds.