Abstract: A series of mesoporous hydrodesulfurization catalysts were prepared using MCM-41 and Ti-MCM-41 as support respectively, Co and Mo as active components. The prepared catalysts were characterized by XRD, FT-IR, Py-IR, UV-Vis and N2 adsorption. Results indicated that the surface acidity of MCM-41 was slightly increased with Ti species introduced, while the surface area and pore volume were decreased. The effect of Ti species on the hydrodesulfurization (HDS) performance of these catalysts was studied on a fixed-bed reactor system using full range FCC gasoline as feed. Evaluation results showed that the HDS activity of catalyst was improved significantly with Ti species introduced. The framework Ti species could inhibit olefin saturation, while the non-framework Ti species could be helpful to increase HDS activity, moreover, synergistic effect existed between these two types of Ti species, thus the catalyst having Si/Ti mole ratio of 14.1 exhibited the best HDS selectivity.