Abstract: Two catalysts, CoMo and NiMoW supported on γalumina, were used to evaluate the hydrodesulfurization effect of three typical diesel oils by analyzing their properties including sulfur content, sulfur compound structures and distributions, nitrogen content and aromatic content. Results showed that CoMo catalyst was more effective in sulfur removal when treating straight run gas oil. In the case of delayed coker diesel and FCC normal light cycle oils, NiMoW catalyst showed a better performance for removing benzothiophene, dibenzothiophene and their derivates than CoMo catalyst. For secondary processed diesel oils, NiMoW showed higher ability for denitrogenation and aromatic saturation compared to CoMo.