Abstract: The selective oxidation method with tetrabutylammonium periodate, separation - X ray fluorescence spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) techniques were used to elucidate the types and distributions of sulfur compounds (thioether, thiophene, DBT, and more complex benzothiophene compounds) in Middle East vacuum gas oil (VGO) and in its 9 fractions before and after hydrotreatment. The results show that sulfidic sulfur accounts for 13.6% of the total sulfur in the VGO, the others are all thiophenic compounds. With increasing boiling point of the fractions，the contents of total sulfur, sulfidic sulfur, thiophenic sulfur and more complex compounds sulfur increase gradually, while the proportion of sulfidic sulfur in the total sulfur of the fractions increases. The alkylthiophenic sulfur, concentrated in lower boiling fractions and the alkylbenzothiophene sulfur decrease as the fraction becomes heavier. Total sulfur content in the VGO is greatly reduced after hydrotreating, the proportions of sulfidic sulfur and benzothiophenic sulfur decrease，while the proportion of more complex sulfur compounds increases. With the increase of hydrotreating depth，the proportions of sulfidic sulfur and alkylthiophenic sulfur decrease gradually and the sulfur content in complex sulfur compounds increases gradually.

Key words: VGO, hydrotreated VGO, sulfidic sulfur, thiophenic sulfur, sulfur distribution