The effects of quinoline and indole on the hydrodesulfurization(HDS)reactivity and reaction routes of dibenzothiophene(DBT)were studied over NiMoS/γ-Al_2O_3 catalyst in a fixed-bed high pressure micro-reactor.The results showed that both quinoline and indole could inhibit the HDS reaction of DBT.They inhibited the hydrogenation route of DBT HDS strongly even at low nitrogen concentration.While the inhibition for the direct desulfurization route only could be seen when the nitrogen concentration increased.The inhibition of quinoline on DBT HDS was stronger than that of indole.The analysis of the products in hydrodenitrogenation(HDN)reaction of quinoline and indole suggested that their inhibition on DBT HDS was closely related to their original structure and the structure of intermediate products in HDN reaction.