A laboratory static culture was conducted in order to better understand the effects of different amounts of nano-carbon on nitrogen transformation and N₂O emission of tobacco-plating soil. The experiment included five treatments on equivalent N basis:CK, ammonium nitrate (N 200 mg/kg); NC1, ammonium nitrate + nano-carbon (2.5 g/kg); NC2, ammonium nitrate + nano-carbon (5 g/kg); NC3, ammonium nitrate + nano-carbon (10 g/kg); NC4, ammonium nitrate + nano-carbon (15 g/kg). The results showed that NC3 and NC4 treatments significantly decreased soil pH value compared with CK (P<0.05). Compared with CK, treatments amended with nano-carbon increased the concentrations of NH₄⁺-N in the early period of incubation and decreased the concentrations of NO₃^--N accordingly. At the end of the incubation, treatments amended with nano-carbon significantly decreased the concentrations of inorganic nitrogen compared to CK (P<0.05). Addition of nano-carbon treatment significantly increased the cumulative CO₂ emissions compared to CK (P<0.05). Compared with CK, NC4 treatment significantly increased the cumulative N₂O emissions (P<0.05). In addition, there was a significant positive correlation between cumulative N₂O emissions and cumulative CO₂ emissions (R²=0.60, P<0.001). The above results indicate that the addition of nano-carbon can decrease soil pH value and the concentrations of inorganic nitrogen, inhibit soil nitrification, improve microbial activity and increase N₂O emissions.