For the traditional packed bed sulfur autotrophic denitrification process has the problems of large filling dosage, serious head loss, easy blockage of the reactor and so on, the nitrogen removal of simulated wastewater by contact denitrification process with sulfur coating was studied. The effects of filler filling ratio, temperature and hydraulic retention time (HRT) on the denitrification performance of the reactor were investigated. The results showed that when the influent NO₃^--N concentration was 50 mg/L, the temperature was (25±1)℃, and HRT=19.5 h, the NO₃^--N removal efficiency was significantly improved with the filler filling ratio increased from 1/10 to 1/5 and the NO₃^--N removal rate increased from 56.77% to 78.26%. Temperature has a great influence on the denitrification in the reactor. When the filler filling ratio was 1/5 and HRT=19.5 h, the average NO₃^--N removal rates were 71.05% and 98.38% at (25±1)℃ and (30±1)℃, respectively. Moreover, when HRT was reduced to 9.7 h, the average NO₃^--N removal rate was 89.29%. During the whole reaction process, the effluent NO₂^--N concentration was very low, kept within 0.4 mg/L. And the effluent pH value of the reactor was maintained between 6.8 and 8.3, which met the pH conditions required for microbial growth. The sulfur autotrophic denitrification dominant bacteria of sulfur coating contact denitrification system were Thiothrixs、Thiomonas and Sulfuritalea, with the proportions of 2.89%,1.55% and 1.35%, respectively. The result of microbial function prediction showed that sulfur and nitrogen metabolism plays a key role in denitrification of the system.