Abstract: β-Mo2N0.78 was synthesized using the reaction of molybdloum oxide with N2-H2 via temperature-programmed reaction. Thiophen hydrodesulfurization(HDS) overβ-Mo2N0.78 was carried out at atmosphere pressure. The results showed that the HDS activity increased with increasing reaction temperature, and pre-reduction could deactivate the catalytic activityβ-Mo2N0.78 also had a resistance to sulfurization. The bulk structure of catalysts did not change after long time HDS reaction. Influence of the synthesis factors including nitriding temperature, nitriding time, N2-H2 ratio and temperature program of nitriding reaction on HDS activity of β-Mo2N0.78 was investigated in detail: (1) the catalytic activity of catalyst decreased with the increasing of nitriding final temperature; (2) the catalyst which was nitrided for a long time at final temperature has low HDS activity; (3) a suitable N2-H2 ratio and a temperature program of nitriding reaction to synthesize catalyst with high HDS activity were determined. It was found that small crystallites of molybdenum nitride had high catalytic activity.