The nitrogen conversion in paddy soil changed significantly during the drying process，but the characteristics and related mechanisms of nitrogen transformation at different soil layers were unclear.In this experiment，the dynamic characteristics of soil redox potential (Eh)，soil N2O concentration and emission flux in upper surface layer (0～5 cm)and lower surface layer (5～10 cm)during 9 days of drying were studied by soil incubation experiment.The abundance changes of ammoxidation genes (archaea amoA and bacteria amoA)and nitrate reductase genes (narG and napA)were determined by real-time quantitative PCR.The results showed that the soil Eh in the upper surface layer increased from -200 to about 500 mV after 9 days of drying，while the soil Eh in the lower surface layer fluctuated from -200 to 0 mV.The decreasing rate of NH4+-N content and increasing rate of NO^3--N content in the upper layer of paddy soil were 2.8 and 1.8 times of that in the lower layer，respectively.In the drying process，ammonia-oxidizing bacteria (AOB)may be dominant in the upper surface of paddy soil，while napA-containing denitrifying microorganisms may be dominant in driving nitrate reduction.