In order to make rational use of ammonium sulfate, we investigated the effects of 3, 4-dimethylpyrazole phosphate (DMPP) combined with ammonium sulfate on nitrogen conversion and N₂O and CO₂ emission in calcareous cinnamon soil. In this study, we analyzed the effects of ammonium sulfate and nitrification inhibitors (DMPP) on ammonium nitrogen (NH₄⁺-N) content, nitrate nitrogen (NO₃^--N) content, N₂O and CO₂ emission flux and cumulutive emission in calcareous cinnamon soil by laboratory culture experiments. The correlation analysis of correlative indexes was also carried out. The results showed that ammonium sulfate was highly nitrated in the first 15 days of culture. At the 15th day, the content of NH₄⁺-N in soil decreased by 477.28 mg/kg, and the content of NO₃^--N increased by 177.03 mg/kg. Addition of DMPP could significantly inhibit the transformation of NH₄⁺-N of ammonium sulfate to NO₃-N. After 30 days of culture, soil NO₃^--N content of 0.75%~1.75% DMPP treatment decreased by 174.02~177.00 mg/kg compared with that of ASN treatment. The nitrification inhibition rate was 94.92%~95.30%, and there was no significant dose effect in the range of 0.75%~1.75% concentration. Each does of DMPP showed better nitrification inhibition effect during the test period, and the duration of action was more than 30 days. When cultured for 30 days, compared with the CKⅡ treatment, the cumulative emissions of N₂O and CO₂ treated with ammonium sulfate alone significantly increased by 975.3% and 126.66%, respectively (P<0.05), while the cumulative emissions of N₂O and CO₂ treated with DMPP significantly decreased by 76.8% and 6.22%, respectively, compared with that treated with ammonium sulfate alone (P<0.05). Correlation analysis showed that there was a positive correlation between CO₂ emission flux and N₂O emission flux,and a negative correlation between soil pH and N₂O and CO₂ emission flux. In calcareous cinnamon soil, ammonium sulfate combined with 0.75% DMPP could inhibit soil acidification to a certain extent, and at the same time could significantly reduce the cumulative emissions of N₂O and CO₂ (P<0.05).