Mixed contamination with antibiotics and antibiotic resistance genes (ARGs) in farmland soil has become an emerging threat against human health and environmental security. However, little attention has been paid on the impact of anoxic denitrification on the dissipation of soil antibiotics and ARGs. Therefore, the present work collected the subsurface mixed-contaminated arable soil around dairy farm, and investigated the influence of denitrification process on the dissipation of soil sulfonamides and their correlated ARGs. The results indicated that nitrate addition to the soil clearly improved the nitrate transforming rate in both soil and water phases, the N₂O production, and the dissipation of soil sulfonamides and ARG abundance. In addition, the clearly negative correlation between the abundance denitrifying genes (nirK, nirS, and nosZ) and sulfonamide resistance genes (sulI and sulII) demonstrated that more sufficient the nitrate nitrogen, the stronger the express of denitrifying genes and the stronger the denitrification process; in order to promote the sulfonamide/ARG dissipation. Moreover, through high-throughput sequencing and the experiment of the separation of denitrifying bacteria, Proteobacteria Lysinibacillus were the predominant strains isolated from anoxic soil among various treatments, which likely played an important role in prompting denitrifying procedure and stimulating sulfonamide/ARG dissipation. This work provided novel information on the anoxic dissipation of soil antibiotics and the ARG proliferation.