Abstract: An alumina carrier with more concentrated pore size distribution was fabricated, and CoMo/Al2O3 catalysts were prepared by wet impregnation method base on the carrier. The effect of nCo/n(Co+Mo) atomic ratio and promoter on catalyst activity was evaluated. The HDS test results reveal that the catalyst with nCo/n(Co+Mo) of 0.3 possesses the best hydrodesulfurization activity and that introduction of promoter into the catalyst can improve the activity of CoMo/Al2O3 catalysts. Based on these results, RMS-30 catalyst with high hydrodesulfurization activity was developed. The pilot plant results show that the relative hydrodesulfurization activity of RMS-30 catalyst increases by more than 20% compared with the previous generation of residue hydrodesulfurization catalyst RMS-1B. The commercial results also prove the better performance of RMS-30 in terms of removal of sulfur and carbon residue.