Abstract: An alumina supported β-Mo2N0.78 catalyst was synthesized via temperature-programmed nitriding reaction in N2-H2 mixture gases. The catalytic activity and selectivity for hydrodesulfurization(HDS) and hydrodenitrogenation(HDN) were studied by using benzothiophene(BT), dibenzothiophene(DBT) and quinoline as model compounds. The experimental results show that the HDS and HDN activity increases with the increasing of reaction temperature and pressure. There is little effect of increasing temperature on HDS selectivity of DBT because of its simultaneous improvement of two parallel desulfurization reactions, direct desulfurization and hydrogenation followed by desulfurization. On the other hand, high pressure favors the progress of the latter reaction. The HDS results of BT and DBT with the addition of quinoline indicate that the addition of N-containing molecule decreases the HDS activity of catalyst and restrains the reaction of hydrogenation followed by desulfurization. With the addition of S-containing molecule, not only the conversion of quinoline improves, but also the HDN activity obviously increases.