Nitrogen fertilizer application，utilization of green manure，and addition of biochar could influence soil nitrous oxide(N2O)emission，this study investigated the impact of the application of their combination on dry land soil N2O emission，providing theoretical support for exploring effective practice to control soil N2O emission.An incubation experiment was conducted，including conventional chemical nitrogen fertilizer(N100)，incorporation of green manure together with 30% chemical N reduced (N70+CV) and its combinations with different kinds of biochar made from sesbania straw (M1)，maize straw(M2)，rape straw(M3)and wheat straw(M4)，respectively.Soil chemical properties，N2O emission flux，nitrification genes(AOA-amoA，AOB-amoA)and denitrification genes(nirK，narG，and nosZ)abundances were measured.Results showed that，compared with N100 treatment，the N2O cumulative emission reduced by 31.2%-71.6% in the N70+CV and the four biochar treatments；Compared with N70+CV treatment，the N2O cumulative emission reduced by 52.0%，43.5%，and 48.2% in M1，M2，and M3 treatments，respectively，the increased by 16.6% in M4 treatment.Compared with N100 treatment，the N70+CV and M1，M2，and M3 treatments increased the content of dissolved organic carbon(DOC)by 52.5%-209.1%，while the content of dissolved organic nitrogen(DON)and nitrate nitrogen(NO^3--N)decreased by 97.0%-99.6% and 97.7%-99.0%，respectively；The pH in N70+CV treatment reduced by 0.03 and the four biochar treatments increased by 0.03-0.07.Compared with N70+CV treatment，the DOC content in M1，M2，and M3 increased by 29.1%，26.1%，and 102.6%，respectively，while the the DOC content in M4 treatment decreased by 22.2%，the ammonium nitrogen content(NH4＋-N)in M2 and M3 reduced by 53.2% and 44.5%，respectively，treatment M4 showed no significance in DON，NH4＋-N，and NO^3--N contents.The pH in the four biochar treatments increased by 0.06 to 0.10.Compared with N100 treatment，N70+CV treatment increased the abundances of soil nitrification genes(AOA-amoA、AOB-amoA)by 46.0% and 388.4%，respectively，and increased the abundances of denitrification genes(nirK，narG，and nosZ)by 203.7%-452.4%，while decreased the ratio of(nirK +narG)/nosZ by 25.4%.Compared with those in N70+CV treatment，the abundance of AOA-amoA in the M1，M2，and M3 treatments was reduced by 33.4%，33.1%，and 57.2%，respectively；The abundances of AOB-amoA in the four biochar treatments reduced by 34.4% to 92.9%，the abundance of denitrification genes showed no obvious regularity，but the(nirK+narG)/nosZ ratio decreased by 16.0%-62.3%.Correlation analysis indicated that the(nirK+narG)/nosZ ratio showed significant positive correlations with soil N2O emission，soil NO^3--N and DON contents，but showed a negative correlation with DOC content.This suggested that the combination treatments enhanced the contribution of denitrification in reducing N2O emission by altering the contents of soil labile carbon and nitrogen content.In short，compared to conventional nitrogen fertilization，cutting 30% of chemical fertilizer nitrogen after incorporation of green manure could reduce soil N2O emission，and combined with biochar made from sesbania，maize，and rape could furtherly strengthen the N2O emission reduction ，the main reason was that it enhanced the soil denitrification process by regulating the content of labile carbon and nitrogen in the soil.